v3 proto: VTGate tests and tweaks
v3 proto: lintification
v3 proto: schema full coverage tests
v3 proto: where.go full coverage tests
v3 proto: insert.go full coverage tests
v3 proto: better errors and full coverate tests for vindexes
v3 proto: simplified router_test
v3 proto: router_test failure cases WIP
v3 proto: more router tests
v3 proto: split router_test into select & dml
v3 proto: more router_test cleanup
v3 proto: router delete full coverage tests
v3 proto: router insert failure tests WIP
v3 proto: moar vindexes

We now have seven vindexes derived from the three
base vindexes (hash, lookup, and numeric).
v3 proto: renamed vindex files to match what they define
Merge pull request #270 from youtube/vtgate

Vtgate