Add options for instance resizing

This patch adds parameterization for three options that are useful
when resizing instances:
* The allow_resize_to_same_host flag allows the source and destination
  hosts to be the same.
* The scheduler_default_filters flag allows users to specify
  nova-scheduler filters.
* The resize_confirm_window flag allows users to have nova
  automatically confirm resizes after some amount of time.

Change-Id: Ib84aa54a5c592fbf9672e34352afbcc95089dd36
Closes-Bug: #1310708
Merge "Add options for instance resizing"