JSCBC-175: Added new behaviour for group method and new group_level method.
JSCBC-175: Added new behaviour for group method and new group_level method.

Note that the new behaviour is backwards compatible with the previous
behaviours, allowing the user to upgrade as needed, though Server 3.0.1
support is not possible with the old behaviour.

Change-Id: Ie753e648178b1d963469b0dcae67eb42c185a2d8
Reviewed-on: http://review.couchbase.org/44987
Reviewed-by: Mark Nunberg <e7d42768707bf23038325b0b68d4b577e5f6064a@haskalah.org>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

GannettDigital/couchnode,brett19/couchnode,KenanSulayman/couchnode,corbinu/couchnode,brett19/couchnode,kshmir/couchnode,kshmir/couchnode,KenanSulayman/couchnode,kshmir/couchnode,Bloutiouf/couchnode,actano/couchnode,KenanSulayman/couchnode,KenanSulayman/couchnode,GannettDigital/couchnode,couchbase/couchnode,brett19/couchnode,corbinu/couchnode,Bloutiouf/couchnode,Bloutiouf/couchnode,actano/couchnode,couchbase/couchnode,corbinu/couchnode,couchbase/couchnode,Bloutiouf/couchnode,couchbase/couchnode,actano/couchnode,GannettDigital/couchnode