webadmin: disable actions in remove brick status pop up after retain/commit

  Disable actions in remove brick status pop up after remove
brick retain/commit is executed.

Change-Id: I2bb9350827e5a288e19e1990a60f67850ae9b290
Bug-Url: https://bugzilla.redhat.com/1029478
Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>