Plates must have a size set correctly

Without the size set on a plate we cannot determine the correct wells.
Add error message for unknown samples
Better sample error handling
Better exception handling
Add seeds value for sequencescape test db
Add decoder for labellable and bulk labellable
Require labellable handler
Add set_barcode_to_a_plate method
Allow labellable messages
Add specs
Bump version to 0.5.0 and use the last version in master branches
Labellable message handler
Use lims-management-app v1.5.1 in master
Fix error message
Merge pull request #14 from llh1/51963363_plate_created_with_barcode

51963363 plate created with barcode
Ensure samples have a created at timestamp
Enable ENV to control environment
Use sanger sample ID as name for a quick fix
Use an environment variable to control environment
Apparently env is in the wrong place!