started implementing of drop api
api encryption part done
renamed plain String; finished deserialisation
finished send part, implemented test.

json part needs a few more looks.
drop-api finished

* added javadoc to the api
* implemented api test
* added more getters and setters

Tests are on ignore for now. Will change when we got a working
drop-server running and I get the credentials (if needed).

TODO: send() is using sendAndForget() for now. Should be changed when we
have a drop ack method.
typo fix
refactored drop-api

* removed class variables
* removed 2nd contructor
* synced javadoc
dropdeserializer now working

shameless stolen from @L-Henke
changed test accordingly to new api
ignore droptests for now (again)
removed unneeded object
changed return of send() from void to int
Merge pull request #74 from jan-schreib/drop-api
Added DropListener and DropController