Some major last minute cleanups. Changed from using TreeMap to ArrayList in the AddressBookPlain-class for simplicity. Added support for editing/updating a contact detail, and more...Ready for release of 0.6.

Minor fixes: Removed synchronized from iterator() in AddressBookDBHandler.java. Updated constructor of ContactDetails.java to make use of the set-methods instead of setting the fields directly. Ready for bugfix release.

Renamed AddressBookDAO to AddressBookDBHandler. Changed the initialisation and use of EntityManager from being a field instantiated once, to be instantiated locally per use.

Updated the readme.md-file, and added a screendump of the application to be added to the readme.md file. Ready for release.