Add limited retype support for rbd

This patch enables limited retype support for rbd. In addition to
basic retyping between volume types that only differ in their name,
retyping between volume types that imply a change of the qos_specs
are supported. This hence allows to adapt the quality-of-service
settings of a volume after its creation.

All other changes, such as host migration, change of encryption or
changes of settings as defined by the extra_specs are not supported
by this commit and left for later patches.

Implements: blueprint ceph-rbd-support-retype
Change-Id: Ib9edf83eb3ade1e6b2dcf1121a16a6f2e68753e1
Get the 'consumer' in a correct way for retyping with qos-specs

The qos specs returned from the database does not contain the
property "qos-specs". Intead, the property "consumer" can be accessed
directly.

Change-Id: I3fe57e5cc20a97d32c8b8c6089ab1e812257da45
closes-bug: #1389519
Merge "Add limited retype support for rbd"
Imported Translations from Transifex

For more information about this automatic import see:
https://wiki.openstack.org/wiki/Translations/Infrastructure

Change-Id: I90527d594081adbd8e32866b39594fda78d5c0e7
Remove Python 2.6 backwards compatibility code

Python 2.6 is no longer supported in cinder as of kilo. The code in the
project that is specifically for compatibility with 2.6 is therefore no
longer required.

This commit removes code referenced as being required specifically for
compatibility with Python 2.6.

This commit removes:
    - total_seconds from cinder/utils.py
    - TestCase.assertGreater from cinder/test.py
    - TestCase.assertGreaterEqual from cinder/test.py
    - StorwizeSVCDriverTestCase.assertLessEqual from
      cinder/tests/test_storwize_svc.py

Change-Id: I2aca4a6a84bc8ddfa70bd47a331b6fac6f82220f
Merge "Get the 'consumer' in a correct way for retyping with qos-specs"
Merge "Imported Translations from Transifex"
Merge "Remove Python 2.6 backwards compatibility code"