MAGMA-240 Implemented for MongoDB datasource
MongoDB test deactivated
MAGMA-240 MongoDB value set updated after variable removal
Fix warnings
Work on GridFS
Add metadata to files
Inspect code
Removed unused private method
USe JSON for binary value metadata
Create MongoDBFactory
Support GridFS
Support binary sequence for Mongo
Complete remove variable test
* Update table & valueSet lastUpdate
* Remove file on variable remove
* Update table & valueSet lastUpdate
* Remove file on variable remove
Merge branch 'dev'

Conflicts:
	magma-datasource-mongodb/src/main/java/org/obiba/magma/datasource/mongodb/MongoDBValueTableWriter.java
	magma-datasource-mongodb/src/test/java/org/obiba/magma/datasource/mongodb/MongoDBDatasourceTest.java