Adding project as group_by (resolves #11 and also #12).
Merge pull request #13 from orviz/add_project

Adding project as group_by (resolves #11 and also #12).
"group_by" configuration parameter out of gecollector scope.
Fix in report.yaml
Use loadables for collectors

Since we are going to have several collectors in the near future we need
a mechanism to automatically load them, and execute them as appropriate
to get the defined metrics. This introduces a new list option "collectors"
that is to be set to the class names of the collectors being used.