webadmin:fix rebalance status dialog disappers issues

 Fixing the rebalance dialog disappearing issue. When user
logout and login, rebalance and remove brick related menu
items are having reference to old UI Command.

   Using ActionButtonDefinition in MenuCell to dynamically
resolve the UI Command.

Change-Id: I98f8660cc080731ce8981eebc04f557c22bbbfaf
Bug-Url: https://bugzilla.redhat.com/1022946
Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>