Removes pre_live_migration need for Fixed IPs

This commit removes the validation that requires Fixed IP Addresses
for pre_live_migration.  The original comment regarding the
pre_live_migration requiring Fixed IP Addresses alluded to uncertainty
about it not being required.  Workloads should not require a Fixed IP
Address for migration, typically just the storage is required to be
similar.

The commit also updates the associated test case to ensure that no
exception is thrown in the pre_live_migration if a fixed IP Address
is not specified.

Change-Id: I2c4d4dae2cb0f00c67f0f731b5080196564b37da
Closes-Bug: #1226226
Fix console db can't load attribute pool

Lists consoles failed when populate console_type from console
db's pool attribute. The reason was db api console_get_all_by_instance
didn't join with pool. So add param 'columns_to_join' for db api, and
join pool attribute when lists consoles.

Change-Id: I18b44860270a401c55cf02b4334b973fbf357b03
Closes-bug: #1223205
Get image metadata in to_xml for generating xml

The to_xml method of libvirt driver will generate xml file of instance
during hard reboot/spawn/rescue/migrate and other operations, and the
image_meta is used for generating correct xml of instance.
But the accurate image_meta may not be passed into the get_guest_config,
so some configs related to the image_meta will be lost, we need to get the
image metadata if it is not passed to the to_xml method.

Fixes bug 1206809
Change-Id: I6942837905334a652cda64d7dd41d3b575846d93
Remove deprecated task states

Task states STARTING and STOPPING were replaced with POWERING_ON and
POWERING_OFF in Grizzly and can now be removed.

Change-Id: I0a29f9aad5689c6401a0f76561cbe46ae2d8e0fb
Merge "Fix console db can't load attribute pool"
Merge "Get image metadata in to_xml for generating xml"
Merge "Remove deprecated task states"
Merge "Removes pre_live_migration need for Fixed IPs"