Deprecate cloudstack.ini configuration

[rvalle]

As discussed,

the current logic with "reading config
from ini file" to get the keys is too error prone and think of
completely getting rid of it.

As a consequence, only ansible parameter (and ansible env vars
fallback) would be available to users to auth

We can use the introduction of Ansible 3 to make this backward uncompatible change

[rvalle]

@resmo shall we say that:

• v1.2.x v2.0.x will require Ansible 3.x
• v1.1.x remaining as Ansible 2.x support

[resmo]

fixed by #64