Updated license header to correctly attribute copyright to Readium Foundation and contributors.
Merge branch 'develop' of github.com:readium/readium-sdk into develop

* 'develop' of github.com:readium/readium-sdk:
  there was a merge problem, so trying to sort out the submodule state...
  Added DAISY Consortium to list of contributors. NOTE: working from develop branch of SDK submodule from LauncherOSX.