Compare string version of types in MySQL

See: https://groups.google.com/d/msg/yesodweb/M1hGNedIvng/VY6gTaNCmt8J
parseType for MySQL keeps original type
MySQL migration: add missing columns #233
Get column type from COLUMN_TYPE instead of DATA_TYPE

Addresses:
https://groups.google.com/d/msg/yesodweb/M1hGNedIvng/5EVWd5U36wUJ
Better round-tripping of types
Adds support for non-BOOL instances of Checkmark

This handles the case where some backends implement BOOL types as either Int64 of ByteString valued columns (notably sqlite).
Merge pull request #249 from orclev/master

Adds support for non-BOOL instances of Checkmark
Added compatibility with 'ExceptT e'.
mongoDB: better null queries

==. Nothing or !=. Nothing

Previously just queried against null,
but it is best to also use $exists
version bump for better null queries
expose anyBsonEq
Keep compatibility with transformers 0.2.1.
Merge pull request #251 from k0ral/master

Added compatibility with 'ExceptT e'.
Merge branch 'better-mysql-migration'
Avoid remigrating Int64
Prevent migrating migrating the schema for mysql numeric type
Merge pull request #252 from MaxGabriel/master

Prevent migrating migrating the schema for mysql numeric type
Merge branch 'master' of github.com:yesodweb/persistent
always use $and at the top of the query

This avoids the case of 2 top-level $or in the object.
Instead a double $or will be sepate objects in an array.

{$or: ..., $or: ...} => {$and:[{$or:...},{$or:...}]}
add MongoRegexSearchable