Erlang internal pubsub server

This server is very simple; what it does is:

• handling subscribers pids in channel state
• publishing a message in a simple list comprehension

Channel name is always binary string.

Usage

(ebus@shizz-laptop)1> C = <<"channel-1">>.
<<"channel-1">>
(ebus@shizz-laptop)2> ebus:start(C).
{ok,<<"channel-1">>}
(ebus@shizz-laptop)3> ebus:subscribe(C).
{ok,<<"channel-1">>}
(ebus@shizz-laptop)4> ebus:publish(C, {message, test}).
{ok,<<"channel-1">>}
(ebus@shizz-laptop)5> flush().
Shell got {message,test}
ok
(ebus@shizz-laptop)6> ebus:unsubscribe(C).             
{ok,<<"channel-1">>}
(ebus@shizz-laptop)7> ebus:publish(C, {message, test}).
{ok,<<"channel-1">>}
(ebus@shizz-laptop)8> flush().                         
ok