Add ability to send generic cec-client commands

[nashant]

No description provided.

[micolous]

This is a really neat idea, but this implementation adds an arbitrary code execution vulnerability:

>>> command="cec_client ';echo 'hello world';#".split(' ')
>>> os.system("echo '{}' | cec-client -s".format(" ".join(command[1:])))

hello world
0

[bkanuka]

You can quote strings and remove the security issues by using shlex.quote

Likewise the split(" ") should probably use shlex.split instead.