Add role for updating meta information of CVMFS servers and repositories

[bedroge]

This role updates the meta info of both the CVMFS Stratums (both 0 and 1) and the repositories (only done on Stratum 0, as this gets stored in the repo itself). See https://cvmfs.readthedocs.io/en/stable/cpt-servermeta.html. Closes #81.

For the server meta info:

# BEFORE:
bob@stratum0:~$ cat /srv/cvmfs/info/v1/meta.json 

{
  "administrator" : "Your Name",
  "email"         : "you@organisation.org",
  "organisation"  : "Your Organisation",

  "custom" : {
    "_comment" : "Put arbitrary structured data here"
  }
}

# AFTER:
bob@stratum0:~$ cat /srv/cvmfs/info/v1/meta.json 
{
  "administrator": "EESSI CVMFS Administrators",
  "email": "support@eessi.io",
  "organisation": "EESSI",
  "custom": {
    "_comment": "See https://eessi.io/docs/ for more information about the EESSI repository."
  }
}

And for the repos:

# BEFORE:
bob@ssr4cc:~$ cvmfs_swissknife info -M -r http://localhost/cvmfs/pilot.eessi-hpc.org
{
  "administrator" : "Your Name",
  "email"         : "you@organisation.org",
  "organisation"  : "Your Organisation",
  "description"   : "Repository content",
  "url"           : "Project website",
  "recommended-stratum0":  "stratum 0 url",
  "recommended-stratum1s" : [ "stratum1 url", "stratum1 url" ],

  "custom" : {
    "_comment" : "Put arbitrary structured data here"
  }
}
bob@ssr4cc:~$ cvmfs_swissknife info -M -r http://localhost/cvmfs/ci.eessi-hpc.org
{
  "administrator" : "Your Name",
  "email"         : "you@organisation.org",
  "organisation"  : "Your Organisation",
  "description"   : "Repository content",
  "url"           : "Project website",
  "recommended-stratum0":  "stratum 0 url",
  "recommended-stratum1s" : [ "stratum1 url", "stratum1 url" ],

  "custom" : {
    "_comment" : "Put arbitrary structured data here"
  }
}
bob@ssr4cc:~$ cvmfs_swissknife info -M -r http://localhost/cvmfs/data.eessi-hpc.org
{
  "administrator" : "Your Name",
  "email"         : "you@organisation.org",
  "organisation"  : "Your Organisation",
  "description"   : "Repository content",
  "url"           : "Project website",
  "recommended-stratum0":  "stratum 0 url",
  "recommended-stratum1s" : [ "stratum1 url", "stratum1 url" ],

  "custom" : {
    "_comment" : "Put arbitrary structured data here"
  }
}

# AFTER:
bob@ssr4cc:~$ cvmfs_swissknife info -M -r http://localhost/cvmfs/pilot.eessi-hpc.org
{
  "administrator": "EESSI CVMFS Administrators",
  "email": "support@eessi.io",
  "organisation": "EESSI",
  "description": "Repository containing pilot versions of the EESSI software stack.",
  "url": "https://eessi.io",
  "recommended-stratum0": "http://rug-nl.stratum0.cvmfs.eessi-infra.org/cvmfs/pilot.eessi-hpc.org",
  "recommended-stratum1s": [
    "['http://rug-nl.stratum1.cvmfs.eessi-infra.org/cvmfs/pilot.eessi-hpc.org', 'http://bgo-no.stratum1.cvmfs.eessi-infra.org/cvmfs/pilot.eessi-hpc.org', 'http://azure-us-east1.stratum1.cvmfs.eessi-infra.org/cvmfs/pilot.eessi-hpc.org', 'http://aws-eu-west1.stratum1.cvmfs.eessi-infra.org/cvmfs/pilot.eessi-hpc.org']"
  ],
  "custom": {
    "_comment": "See https://eessi.io/docs/ for more information about the EESSI repository."
  }
}
bob@ssr4cc:~$ cvmfs_swissknife info -M -r http://localhost/cvmfs/ci.eessi-hpc.org
{
  "administrator": "EESSI CVMFS Administrators",
  "email": "support@eessi.io",
  "organisation": "EESSI",
  "description": "Small-sized epository used for CI purposes.",
  "url": "https://eessi.io",
  "recommended-stratum0": "http://rug-nl.stratum0.cvmfs.eessi-infra.org/cvmfs/ci.eessi-hpc.org",
  "recommended-stratum1s": [
    "['http://rug-nl.stratum1.cvmfs.eessi-infra.org/cvmfs/ci.eessi-hpc.org', 'http://bgo-no.stratum1.cvmfs.eessi-infra.org/cvmfs/ci.eessi-hpc.org', 'http://azure-us-east1.stratum1.cvmfs.eessi-infra.org/cvmfs/ci.eessi-hpc.org', 'http://aws-eu-west1.stratum1.cvmfs.eessi-infra.org/cvmfs/ci.eessi-hpc.org']"
  ],
  "custom": {
    "_comment": "See https://eessi.io/docs/ for more information about the EESSI repository."
  }
}
bob@ssr4cc:~$ cvmfs_swissknife info -M -r http://localhost/cvmfs/data.eessi-hpc.org
{
  "administrator": "EESSI CVMFS Administrators",
  "email": "support@eessi.io",
  "organisation": "EESSI",
  "description": "Data files used for applications available in the EESSI stack.",
  "url": "https://eessi.io",
  "recommended-stratum0": "http://rug-nl.stratum0.cvmfs.eessi-infra.org/cvmfs/data.eessi-hpc.org",
  "recommended-stratum1s": [
    "['http://rug-nl.stratum1.cvmfs.eessi-infra.org/cvmfs/data.eessi-hpc.org', 'http://bgo-no.stratum1.cvmfs.eessi-infra.org/cvmfs/data.eessi-hpc.org', 'http://azure-us-east1.stratum1.cvmfs.eessi-infra.org/cvmfs/data.eessi-hpc.org', 'http://aws-eu-west1.stratum1.cvmfs.eessi-infra.org/cvmfs/data.eessi-hpc.org']"
  ],
  "custom": {
    "_comment": "See https://eessi.io/docs/ for more information about the EESSI repository."
  }
}

[trz42]

Looks good. Tiny typo. Should be easy to fix.