engine:Add dao method to update task on brick

Added a dao method to update task on brick given
a brick's server id and brick directory
A batch method introduced to update all bricks with
a task id.

Change-Id: I3abd6d4a3649a8c4880e2fdbde190ab1d2268c06
Signed-off-by: Sahina Bose <sabose@redhat.com>