small adjustments on path, db_port and servicegroup object

I made little adjustements 
- to have the default path in all objects reflecting the directories created in server.pp
- in the doc there is a db_port parameter for the server : I add it in server.pp definition and params.pp
- I need servicegroup object : I add it

I edited with gepetto with lint autocorrection activated so it has reformat every file.

Tested on centos