VMware: Fix volume detach failure

The VMwareVCDriver method "detach_volume" is missing the "encryption"
argument and thus does not conform to the driver API. Adding the missing
argument solves TypeError being thrown when detaching a volume.

Change-Id: Ib785c2b2cf4c25deed272f8e3f0f47abe6139d1c
Closes-Bug: #1226826
Add tests for pre_live_migration

Add tests to ensure retrying plug_vifs in pre_live_migration works.

Closes-bug: #1228749
Change-Id: I80d4cdc27836511c55b2555556edd7a1964c7158
Fix indentation in virt.libvirt.blockinfo module

Fixes confusing indentation in is_disk_bus_valid_for_virt function where
leading 8 spaces were used instead of 4.

Change-Id: Ic320dc6860b1efa7464d631c4c649be13d7206a1
Merge "VMware: Fix volume detach failure"
Merge "Fix indentation in virt.libvirt.blockinfo module"
Merge "Add tests for pre_live_migration"