Enable Nova v3 API

The Nova v3 API will be disabled by default after 31164 goes through.
This change explicitly enables the v3 API in the nova config file

Change-Id: I8b4c64b4718fc96d7a928c6fa3a0e8716c7edba1
ceilometer does not set db in conf file

Set [database]connection option to mongodb rather than sqlite as mongodb
is the only fully supported db.

Change-Id: I2b9fbc65de4476593d456a782dbc7e6540a75141
Fixes: bug #1186240
Merge "Enable Nova v3 API"
Merge "ceilometer does not set db in conf file"