input now clears if barcode scanned is of invalid length
when creating a manifest, only integers are accepted in the input for number of tubes to create
minor modification
if tube not found, a message is given to the user. barcode errors now all use the manifest_reader_presenter's messaging function for consistency. tests updated accordingly
tests reordered for clarity
Merge pull request #217 from david-allen-tessella/reception_app_tests_fix

Reception app tests fix