Enable a forum moderator to move topics. Bug 1380003

A forum moderator now can move topics around forums to which he/she is
assigned

Change-Id: I6a38cb9571aaa69ed03a307f184eca3124801ead
Signed-off-by: Son Nguyen <sonn@catalyst.net.nz>
Merge "Enable a forum moderator to move topics. Bug 1380003"