Enables db2 server disconnects to be handled pessimistically

A checkout listener can be added to sqlalchemy to be able to handle
database disconnect pessimistically and avoid an error in the event of
a DB restart or simply a temp connection issue due to network
glitches. At the moment only mysql is enabled with this feature. This
patch enables db2 as well.

Sync oslo db.sqlalchemy from commit：
bb4d7a2534f6087d828e22784dc263522d309592

Partial-Bug: #1231657

Change-Id: Ib89de07f004975528baffdfd19aae689b089a324
Convert [Cinder]Volume to new Schema format

blueprint property-schema-conversion

Change-Id: Ia7d9e995cf78cc3425cf278d19700451a3347a26
Fix stack_get_by_name does not list nested stack issue

The nested stack's owner_id is not None. When querying a result
filtered with owner_id=None, then nested stacks will not be
listed. The fix is to filter stack_get_by_name by stack name only and
add a new API stack_get_by_name_and_owner_id to filter via stack name
and owner id.

Change-Id: I659104f4936b567222108c211f77473ef35638c6
Closes-Bug: #1240892
Improve autoscaling error message

If we can't find the autoscaling group name produce a more
meaningful error message.

Change-Id: Id7ecae67c9ca8eca0c45b365e9a58caee212c2c9
Closes-bug: #1260111
oslo: add the crypto module

This is to be used instead of the hand rolled heat/common/crypt.py.

Partial-bug: #1251647
Change-Id: I622b9d0c942075f99fdbaff470906123c631504a
Imported Translations from Transifex

Change-Id: I3e551f9c9eb4f5b81f58f5503218665f2b80b0d1
Merge "Convert [Cinder]Volume to new Schema format"
Merge "Enables db2 server disconnects to be handled pessimistically"
Merge "oslo: add the crypto module"
Merge "Fix stack_get_by_name does not list nested stack issue"
Merge "Improve autoscaling error message"
Merge "Imported Translations from Transifex"