apphandler: channel: split out commands

I split out the channel commands into their own
subordinate file from the apphandler.cpp.  There
are three commands in apphandler for the channel
information.  There are other commands in the
transporthandler that correlate.

Moving this is step one in a larger task to enable
multiple channels.

Change-Id: I2e434a1da942325fc420079415edb39622f4e346
Signed-off-by: Patrick Venture <venture@google.com>
5 files changed