Lots of minor changes.
- Added automatic retrieval of B&N key from nook Study log file
- Added in latest version of obok plugin for Kobo kePubs
- Fix for ePubs with non-ASCII internal files names (thanks to Jose Luis)
- Fixed preferences creation for Mac DeDRM app on Mac OS X 10.10
- Fix problem initialising DeDRM plugin
- Fix problem when trying several B&N keys in DeDRM plugin
- More logging of errors in DeDRM plugin
- Better handling of PDF decrypting in DeDRM plugin
- Updated ReadMes