OpenStack: update gophercloud package and add new auth options

[kayrus]

Description

This PR adds new auth options into the openstack client and removes deprecated keystone V2 support.

Additionally it adds an ability to remove the VM, which was not created successfully. If it is not removed, new VMs cannot be created, because the resources quota can be reached.

Related issue(s)

Resolves #3774 and rancher/rancher#15796

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "gophercloud" git@github.com:kayrus/machine.git somewhere
$ cd somewhere
$ git rebase -i HEAD~842354383416
editor opens
change each 'pick' to 'edit'
save the file and quit
$ git commit --amend -s --no-edit
$ git rebase --continue # and repeat the amend for each commit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[DJAyth]

Could really use this as well, since it's causing me major pains. Can someone look at it?

[kayrus]

Closing in favor of rancher#54
/cc DJAyth