Revamp documentation, add module references

Documentation is modeled after python-novaclient docs.
(http://docs.openstack.org/developer/python-novaclient/)

Built preview for reviewers:
https://nsaje.fedorapeople.org/python-ceilometerclient/

Change-Id: I61e9d6593e4a1aea5cf018081416d4be3a9372ac
Merge "Revamp documentation, add module references"