Add a tox job for generating docs

Add a tox job to make it easier for developers to generate their
own docs before submitting a patch.

Change-Id: Icbfd5ee5556a9c344ebe9ca7f4b579a87ad2d01b
Change "Connection refused" to "Connection error"

The python-requests documentation indicates that the
ConnectionError exception can be raised for reasons other than
"connection refused".  Let's just say "error" rather than
implying the wrong type of failure.

Change-Id: I2205e27c7c68164db430cdfdc71b57b3002b24be
Update theme for docs

The current developer docs theme used is out of sync with the other
openstack projects. This patch will update the docs to provide a more
consistent look and feel when using developer docs

Change-Id: I9fd11b61d4404ba2627569074dc86ee0ddf0f96a
Fix the return code of the command reset-state

Currently, the command reset-state return code is zero if it
failed for any of volumes, it should be nonzero.

Change-Id: Ic6da238861fd003375003399bc6def6bf860a015
Closes-Bug: #1339643
Merge "Fix the return code of the command reset-state"
Merge "Add a tox job for generating docs"
Merge "Change "Connection refused" to "Connection error""
Merge "Update theme for docs"