FEATURE: Create new commands to simplify daily operations

[Masber]

Propose of new commands under a new verb set for most common operations while managing clusters

manta set <target> [-H <hsm group name> | -x <list of xnames>] <operation>

eg:

manta set runtime_configuration -H my-hsm my-configuration

manta set runtime-configuration
manta set boot-confguration
manta set boot-image
manta set kernel-parameters

NOTE:
We could define HSM or xname list as an argument or as a subcommand. This is an open discussion.

eg:

# subcommand examples
manta set runtime-configuration cluster my-hsm my-configuration
manta set runtime-configuration nodes x1,x2 my-configuration

# argument examples
manta set runtime-configuration -H my-hsm my-configuration
manta set runtime-configuration -x x1,x2 my-configuration