Added the config.rb generation, improved config.rb detection

Added 3 features
 - The plugin will now search a config.rb file in the parent directory recursively (searching in parents directory)
 - The plugin will now refresh CSS depending of the command output. Can refresh multiple CSS for instance.
 - Added a compassplugin.sublime-settings to tweak some parameters, like the config.rb regeneration that was removed in a previous version so people that want this feature can just enable it.