Add more fields needed by Aquilon

* Complete the sysloc structure
* Add feature parameters to /system/features
* Add sysloc and rack to the clusters
Make the host_environment in personalities optional
Make node_index optional
Merge pull request #14 from piojo/aquilon-more

Add more fields needed by Aquilon
Merge pull request #6 from quattor/master

update schema structure_sysloc