Properly write non-raw LVM images on creation

Fixes bug 1075333

When force_raw_images=False and libvirt_images_type=lvm were set
together, selecting anything other than a RAW image would result in
an unbootable instance. This is because the downloaded image was
being directly dd'd onto the new LVM root, which will obviously not
work for any format other than RAW.

Simple change to use qemu-img to read from the image (letting it
decide the format) and write to the LVM root as raw.

Change-Id: I36494e6d0671c07f7511c10ef886c8cf84c18df7
Remove locking declarator in ServiceGroup __new__()

The lock-based synchronization is not re-entrant, which
would introduce a deadlock with the new conductor patch.
Because race condition is not be possible in the
eventlet threading model with GIL, we simply remove the
synchronized declarator.

Change-Id: I03e52227385dafd2b2b66bca18cab8445c91f3be
Merge "Remove locking declarator in ServiceGroup __new__()"
Merge "Properly write non-raw LVM images on creation"