Use oslo db concurrency to generate nova.conf.sample

Make sure we include database and concurrency options in the
sample config file.

Change-Id: I66e68ec120cba2cee86e36aa26720199876c40a4
Closes-Bug: #1391782
libvirt: move setting of clock out into helper method

Move clock settings will be added in the future, so it
makes sense to have a separate helper method for all
of them.

Related-bug: #1400315
Change-Id: I1662e2d1e2e729da873c14a0cc307e412c699320
Adds support for versioned schema validation for microversions api

Adds the ability to specify minimum and maximum API microversion
versions on jsonschema validation decorators. Validation will
only occur through the decorator if the incoming request version
matches the version range specified. If no range is specified then
validation will always occur.

Partially implements blueprint api-microversions

Change-Id: Ia71963161966af3ca0e6e30e2245f12120f8f8d1
Merge "Use oslo db concurrency to generate nova.conf.sample"
Merge "Adds support for versioned schema validation for microversions api"
Merge "libvirt: move setting of clock out into helper method"