Add a wadl target to the documentation

Thanks to sphinxcontrib-docbookrestapi, the documentation for the REST API can
be automatically generated. Add a target to do this.

Change-Id: I9dda41bc00160bf1be1e275d9ac94a3a53571688
Remove redundant code in nova_client.Client

'a and a or b' is equal to 'a or b', the redundant code can be
removed.

This patch also fixes the docstring of __init__, which actually
initializes a nova client object, not returns.

Change-Id: I0815928a2b597452048a1cc6c2170259a53ccaf9
Closes-Bug: #1264099
Add missing gettextutils import to ceilometer.storage.base

Change-Id: I1cea5f9032ffceac72cd441da81f197e7f66448d
Closes-Bug: #1265492
Change endpoint_type parameter

Replace endpoint_type parameter by os_endpoint_type parameter
expected by ceilometerclient.

Change-Id: I676247b289f8efa7c047a34dc9333361d094b024
Closes-Bug: #1257232
Merge "Change endpoint_type parameter"
Merge "Add a wadl target to the documentation"
Merge "Remove redundant code in nova_client.Client"