Added KeyRange class to represent the KeyRanges and modified the test.
Added bson encode and decode functions for KeyRange Arrays.
Added function to derive shard name for SrvShard.
Api, functional changes and test for StreamExecuteKeyRange.
Replaced SessionId to Session to make it compatible with previous protocol changes.
Changed StreamQueryKeyRange to accept only one keyrange.
Support and test for non-sharded db.
Small fix to util functions.
WIP vtgate integration test and client change to support new streaming api.
Change in api for StreamExecuteKeyRange and vtgate tests.
Post-merge fixes.
minor test fixes