Move compressor into a plugin

The compressor was included deeply into the server, but we can move it
into a plugin, so then we can enable/disable it or develop independently
from the jms.
Make possible to pass arguments for a plugin

You may need to configure a plugin by passing options to it.
Set a "options" parameter to the plugin config, it will be passed as the
second argument to the plugin constructor.
Merge pull request #2 from Ajnasz/compressor-to-plugin

Move compressor into a plugin