- adds sending of accept- and reject-events
- adds fit-connect problems

- enables end-2-ed encryption by encrypting outside the sdk with the destinations public key 
- send encrypted data to the sdk that handles further submit of the submision data

refactor(validation): move data validation and null checks from sender strategies to sender client to fail fast

chore(validation): remove runtime exception through precondition check. Initialisation should be checked by calling instance

- Rework der Applicationconfig zu yaml

Feature/15 Java SDK MVP Part I: contains implementations for sending & subscribing to submissions, adds commandline client