Skip none value attributes for ec2 image bdm output.

Fix crash in _format_block_device_mapping when there are None values
for formatting attributes in the mapping.

Change-Id: I0ebdb844d75cdf1580cc88e1ff40fc21aff96f21
Closes-Bug: #1323403
VMware: Remove ds_util.build_datastore_path()

Convert all remaining users of build_datastore_path to use the
DatastorePath class, and remove build_datastore_path() and its tests.

Change-Id: I73a166a48c0038743213e4feaa95834f9ebc8fbf
VMware: test_driver_api: Use local variables in closures

Some closures were unecessarily storing constants used by closures in
the test object. This change converts them to use local variables
instead. Values which are modified remain in the test object.

Additionally, 1 unused value is removed.

TrivialFix

Change-Id: I0164bf23f4d51505871cee8db170b73534410c4a
Neutron v2 API: fix get_floating_ip_pools

Commit 7254f9b9dfbadadeb3aeda5d02bf37bfeb65e72d changed this method
in nova.network.api in a way that it now returns simply a list of
floating ip pool names, rather a list of dicts in the form

{'name': 'pool_name'}

The implementation of get_floating_ip_pools for neutron needs to
be changed accordingly. Otherwise nova's floating ip extension
will return a dict as floating ip pool names when neutron is enabled.

Change-Id: I27001c9f17dad4dc4ca8cd032e689736553d8225
Closes-Bug: #1355882
Merge "Skip none value attributes for ec2 image bdm output."
Merge "VMware: Remove ds_util.build_datastore_path()"
Merge "VMware: test_driver_api: Use local variables in closures"
Merge "Neutron v2 API: fix get_floating_ip_pools"