Private and public group implemented
Merge branch 'mongokit' of https://github.com/gnowledge/gstudio into mongokit
Retrieval-query modified.
Merge pull request #171 from makfire/mongokit

Private and public groups implemented
Bugs removed in homogeneous collection module
Merge pull request #172 from sunnychaudhari/mongokit

Bugs removed in homogeneous collection module
Merge branch 'mongokit' of https://github.com/gnowledge/gstudio into mongokit-amn-edv
Minor changes.
Changes regrading implementation of migration script for member_of field.