Merge pull request #66 from jonathangreen/1.x

Add tuque to composer.
Merge pull request #67 from jonathangreen/1.x

Fixed bug in datastream version isset.
just a typo
Merge pull request #68 from ruebot/1.x-checksum-typo

just a typo
Fixed bug in FedoraRelationships

When an object had no models, and a relationship was being added
it was possible to get into a state where the content of the
RELS-EXT datastream was overwritten.