Small bugfix in SLIM + add fogotten file to slim's Makefile.am
Forgotten file was the PID list file
The bugfix concerns the conf when selection mongodb as datasource (quick & dirty solution : keep dummmy_datasource loaded so we don't have to modify the original datasource conf)
Bufixes in start & stop functions
Add a -f --foreground option allowing to run an instance in foreground
There is one problem left : the unix socket creation is not done in the instance directory...