Allow setting of compute configuration options

* image_cache_manager_interval     - Number of seconds to wait between
                                     runs of the image cache manager.
* resize_fs_using_block_device     - Attempt to resize the filesystem by
                                     accessing the image over a block device.
* resume_guests_state_on_host_boot - Whether to start guests that were
                                     running before the host rebooted.
* running_deleted_instance_action  - Action to take if a running deleted
                                     instance is detected.
* virt_mkfs                        - Name of the mkfs commands for ephemeral
                                     device.

Change-Id: Ib9108978ec306d5ccda0a410e519dbc88eb9ff11
Merge "Allow setting of compute configuration options"