added travis file and updated README
updated travis file
Merge pull request #94 from philsogaDGI/7.x

Setup Travis and Tests
Implement derivatives hook.
Add function comment and get rid of unused variable.
Carry through changes of Islandora constants.
Merge pull request #96 from adam-vessey/7.x-constants

Carry through changes of Islandora constants.
Merge pull request #95 from adam-vessey/7.x-derivatives

Implement derivatives hook.