Remove usage of locals() from xenapi package

fixes bug 1171936

Some minor formatting cleanup was done as well

Change-Id: If52c2bf1eb38b5d0072a783bd944304576a70d13
Backup and restore object registry for tests

Without this, the object registry can become cluttered with test objects,
which may conflict with each other, depending on the order and pairing
of testr processes.

Related to unified-object-model

Change-Id: I77d3beebfb963cdc24c49eebb38ca8a768c69503
Fix obj_load() in NovaObject base class

The obj_load_attr() method is correctly used in the field getter,
but incorrectly provided in the base class (without the _attr
suffix). Rename that and add a test for the base class that makes
sure this method gets poked appropriately.

Related to blueprint unified-object-model

Change-Id: I3b010ef727fed2f59fbb3d7173078b1dbc4b81f6
Merge "Backup and restore object registry for tests"
Merge "Fix obj_load() in NovaObject base class"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp