Added SQL parser based on vitess's SQL parser.

Local changes include support for a bit more of the SQL language and
some naming changes to make this package be almost lint free. Note that
there is a remaining bit of lint in the generated sql.go file that I
cannot get rid of because it is generated by yacc (yyEofCode should be
named yyEOFCode).
Add an env variable that allows pre-commit to be skipped.

Only for use in emergencies (e.g. code that files lint that we can't
fix).
Generate sql.go from sql.y.
Rename TODO to TODO.md

This makes it nicely viewable as markdown
Merge pull request #70 from pzurek/patch-1

Rename TODO to TODO.md
Update README.md
Merge pull request #71 from pzurek/patch-2

Update README.md to point correctly to TODO.md file
Merge pull request #69 from petermattis/sqlparser

Sqlparser
Address Ben's comments.
Handle case in MVCC of encountering a value written during same txn but
an earlier epoch. In this case, we want to read the original value
instead, so we scan for the next value prior to the intent.
Added log statement for resolving write intents.
Merge pull request #72 from cockroachdb/spencerkimball/resolve-write-intents

Push Txns & Resolve Intents on Conflicts
Renamed scanNext to scanNextVersion.
Merge pull request #73 from cockroachdb/spencerkimball/txn-read-with-diff-epoch

Handle case in MVCC of encountering a value written during same txn but
Fixed error in commit 9ed5dbc.
WIP transactional DB
WIP on transactional kv.DB.
Merge branch 'spencerkimball/txn-db-impl' of https://github.com/cockroachdb/cockroach into spencerkimball/txn-db-impl

Conflicts:
	kv/db.go
	kv/txn_db.go
	storage/store.go