Add initial documentation for readthedocs

[JohnStrunk]

Describe what this PR does

• Updates Travis to check documentation
• Provides skeleton for project documentation

Is there anything that requires special attention? Once this merges, It'll populate readthedocs. I have set up the account & webhook already. Documentation has been built/viewed locally and checked by Travis, but we won't know for sure until the first build by rtd.

Related issues: Fixes: #4

[JohnStrunk]

I was sad to see that there was already a "anthill.readthedocs.io"... So we have to be gluster-anthill.readthedocs.io :frowning_face:

[humblec]

@JohnStrunk in one way, gluster-anthill.readthedocs.io looks good to me. It give some tie up to gluster product search.

[humblec]

/assign @humblec