Fixed missing Launch as Instance for snapshot

The snapshot created from a bootable volume doesn't have 'Launch
as Instance' action item show up.

Fixed the issue, now the snapshot created from a bootable volume
should have the 'Launch as Instance' action item.

Note: for how to create a bootable volume, please check the bug
detail.

Closes-Bug: #1369189

Change-Id: I2a085c6fc07a4b08b1cb0fc61ad82a1dfa14af65
Merge "Fixed missing Launch as Instance for snapshot"