Capture exception when delete a volume detached

Currently, the cinder api validate volume state before validating volume
attach status, so the VolumeAttached exception will never be raised. this
patch change the order of validation to fix this issue.

Change-Id: I41451f5f9d8e60b3cfc1a8004b704285fc3ddc2b
Update prerequisite packages in development docs

The packages listed for Linux distros are updated to meet the
prerequisites to run the unit tests.

Change-Id: Iedd9e4d04d7700d418ddb07881ac76ad758466cb
Closes-bug: #1367670
Imported Translations from Transifex

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

Change-Id: Iacc17652260172c2888d71026e316a53e135b9b7
Use oslo.utils

oslo.utils library now provides the functionality previously in
oslo-incubator's excutils, importutils, network_utils, strutils
timeutils, units etc. Some of these outdated modules will still be
around for a while until all other oslo modules that use them have been
updated in future commits.

Change-Id: Idee8600dfe42e5977b8fb824e91afff7e9119981
Switch Cinder to use oslo.concurrency

Let's switch to the newly released oslo library for the
processutils and lockutils. We use the config fixture(s) to
specify disable_process_locking and lock_path in the CONF
variable of oslo.concurrency library for correctly setting the
flags.

Change-Id: Ib8f3aac5449eba66ea84bc5cad8aea061adab276
Merge "Capture exception when delete a volume detached"
Merge "Use oslo.utils"
Merge "Switch Cinder to use oslo.concurrency"
Merge "Imported Translations from Transifex"
Merge "Update prerequisite packages in development docs"