Add a command line receiver

[Tijani-Dia]

Add a command line receiver.

Example:

$ ./manage.py live create-channel my-channel
$ channel my-channel created
$ ./manage.py live post my-channel "here's my first message"
$ message 4125 posted
$ ./manage.py live edit my-channel 4125 "new message text for first post"
$ message 4125 updated
$ ./manage.py live delete my-channel 4125
$ message 4125 deleted