Misc fixes for v3 evacuate API extension

Miscellaneous fixes for the V3 evacuate API extension:

- Python style attribute naming
- admin_password is no longer an optional return value. If it
  is not set it is returned as None

Partially implements blueprint nova-v3-api

Change-Id: Ida5da71bddd495880bafd90a578ca95b21319504
port Deferred_delete API into v3 part1

This changeset only copies the v2 files into the appropriate v3
directories unchanged. The copy as-is will not be loaded by either
the v2 or v3 extension loaders. The second changeset will then
make the changes required for it to work as a v3 extension.

This is being tried in order to make reviewing of extension
porting easier as gerrit will display only what is actually
changed for v3 rather than entirely new files.

Partially implements: bp v3-api-extension-versioning

Change-Id: I43de158d32c03ffa416699e7f6835a7dbcd9e6bd
Merge "Misc fixes for v3 evacuate API extension"
Merge "port Deferred_delete API into v3 part1"