Fix strict warning.
Use hooked access callback to make GUI respond.
Merge pull request #45 from adam-vessey/7.x-hooked-access

7.x hooked access
Travis for Fedora 3.6.2
Merge pull request #46 from willtp87/7.x.travis

Travis for Fedora 3.6.2
Implement derivatives hook.
Carry through changes of Islandora constants.
Merge pull request #49 from adam-vessey/7.x-constants

Carry through changes of Islandora constants.
Merge pull request #48 from adam-vessey/7.x-derivatives

Implement derivatives hook.