Adds ephemeral_key_uuid field to instance

Patch adds a field to instance for storing the uuid of
the key used to encrypt instance's ephemeral storage.

Implements: blueprint encrypt-ephemeral-storage
Change-Id: Id5b1e272d4461875bb231839e4714d3ed0899d3f
Adds dmcrypt utility module

Patch adds a module for manipulating dmcrypt devices.

Implements: blueprint encrypt-ephemeral-storage
Change-Id: I308b9f26c382b332c02f13aa1d5f0a830e9ef277
Remove v3 xml API sample tests

This is a step toward removing XML support from the v3 compute API.
First, we need to remove all of the tests that would fail once we start
ripping out the real code.

Part of blueprint remove-v3-xml-api

Change-Id: Ie2c280d5ea1e6b8756535deb05982a92561552db
Remove xml unit tests for v3 api plugins

Remove a bunch of unit tests for XML support in v3 compute API plugins.
This is another step towarding removing XML support completely from this
API.

Part of blueprint remove-v3-xml-api

Change-Id: Ibc35791cd8593b523ff21d9f604d0263e6da2b0a
Merge "Remove v3 xml API sample tests"
Merge "Remove xml unit tests for v3 api plugins"
Merge "Adds ephemeral_key_uuid field to instance"
Merge "Adds dmcrypt utility module"