Remove useless host parameter in virt

For host api, there are useless host params for
host_power_action and set_host_enable virt API,
this patch removes the useless host params.

Change-Id: I556278fc426a800f108da9129e42175da32dac49
Fix live migration api stuck when migrate to old nova node

Commit bc45c56f102cdef58840e02b609a89f5278e8cce disable instance
live migration between different verison node. If the two nodes
with different rpc version, will raise exception
LiveMigrationWithOldNovaNotSafe. But this exception didn't catch
as expected exception, that make the instance status stuck at
migrating. This patch add LiveMigrationWithOldNovaNotSafe as
expected exception.

Change-Id: I1dcee9181fd0ef293628b30766112f00792796ab
Closes-Bug: #1377644
Virt: update spawn signature to pass instance_type

This patch updates the spawn method to receive the instance type
as input. This will save database calls when spawning instances.

This is due to the fact that a number of the virt drivers are now
reading the flavor extra specs. There is no need to access the
database to get this information.

An example of where this will be used is
commit af4ec4ccb1ce5e635171c1d4b39f37fe0a5ccc34.

Change-Id: Ieebfcbc2478ba8d7036c1af30efbbf640aa7df73
Merge "Virt: update spawn signature to pass instance_type"
Merge "Remove useless host parameter in virt"
Merge "Fix live migration api stuck when migrate to old nova node"