Add library types tables
Library_types_request_types_has_id
Add basic models and seeds
Batch validation use request type
Merge branch 'production' of github.com:sanger/sequencescape into refactor_batch_validation
Update metadata to use associations

This one was a bit of a pain as metadata validation
is set up at the time of class definition. Should
probably revisit this once I've extended it to eg.
read length
Strip out hardcoded Library Types
FieldInfos use instance level properties where
appropriate
Add request option validators
Merge pull request #5 from JamesGlover/refactor_request_validation

Refactor request validation