Add check for BlockDeviceMappingV2 nova extension

Booting instance from image (creates a volume) option is using
the new BDM format when submitting the create server request to
Nova. Adding a check for Nova extensions if it is supported
before displaying the option.

Change-Id: Ie0b2b5d574babc910e2dac7ce9e3ab6603382ffb
Closes-bug: 1223875
Abstraction of Ceilometer meters information

- Extract the metadata of the meters to a class (label,
  description)
- The list operation support (only, except) filter
- It supports listing meters by their service e.g. .list_nova(),
  .list_neutron()

- Tests for meters list written.

Fixes bug 1226479

Change-Id: Ifa366fd2de3e8f4e31347962630f96344ebba974
Merge "Abstraction of Ceilometer meters information"
Merge "Add check for BlockDeviceMappingV2 nova extension"