Merge pull request #44 from sanger/next_release

Update barcode format
Merge pull request #46 from sanger/next_release

Revert tube barcode to old format
Do not yield when no label type

We don't want a label_type field, so we don't yield. If we
yield nil we still run the block.
Merge pull request #47 from JamesGlover/don_not_yeild_nil

Do not yield when no label type
Fix multi barcode form
Merge pull request #48 from JamesGlover/correct_multip_barcode_form

Fix multi barcode form
Merge pull request #49 from sanger/production

Production