VTGate V2 implementation and sandbox test improvement
Merge branch 'master' into liguo

Conflicts:
	go/vt/vtgate/proto/vtgate_proto.go
Store a history of health.Run results.
Allow history.History to deduplicate records.
health.Record: define methods for display and deduplication.
Fix typo in health.Record.Class.
health.Record.Class: really fix it, write test.
Fix silly bug in health module.
WIP connection and cursor class for vtgate v2.
Added additional methods and cleaned up some code.
Small fixes.
more cleanup.
Added function to convert shard_name to keyrange.
queryservice: support lock in share mode construct
queryservice: qualified column names in insert
Update VTGate V2 with keyspaceid and keyrange queries
Convert read-only error to OperationalError
bug fix: SHARE and MODE are not keywords

Looks like share and mode are valid column names even though
LOCK IN SHARE MODE is a special construct. So, we can't treat
SHARE and MODE as keywords. Otherwise, the parser fails for
columns with such names.
Update GettingStarted.markdown
First pass at MariaDB support.

test/tabletmanager.py passes!
It's enabled by setting MYSQL_FLAVOR=MariaDB before anything.