parser: improved tests & error messages (WIP)
parser: tokenizer tests and a bug fix
parser: failure cases for tokenizer (WIP)
parser: add missing test file for tokenizer
parser: stream plan & parsed_query tests

Coverage is at 94%. All required code paths
are now fully covered in sqlparser.
Merge branch 'parser'
Merge branch 'master' of github.com:youtube/vitess
Fixing keyspace rebuild to operate on the right cells.

Used to get the list of cells by looking at the cells that
contain a serving tablet in shard 0. Now use the intersection
of the union of all shard.Cells and the passed-in cell list.