Enh : Rename plugins

Please review it. We need to rename everything in OBS then.

* The name is closer to monitoring-plugins (formerly nagios-plugins) package so that we keep some standard
* Monitoring-plugins is a great name because it's very generic and does not rely on a backed (Shinken etc), plugin-check-XXX is not self explainatory. 
* monitoring-plugins-sfl-XXX is more convenient for package listing / search. It looks like it's a sub category of monitoring-plugins which  is clear and prevent name conflicts.