Add 5 more channel commands

We now support the following commands:

   channel-exit
   channel-hold-add
   channel-hold-remove
   channel-mute-add
   channel-mute-remove

Change-Id: I2d676a72ec7bc499527ae0ec62c3e79eeeeb0d32
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>