fix NullPointerException in MessageMonitor
Fix serializer for FileReqResp model
improve logging in MessageDeserializer
Remade ITransferProgress and Download-Stuff

See state diagram in lucid charts for more details
Add Mocks for unittesting

message observer mock exposes all received messages
network mock exposes incoming buffer and can send bytes back
add tests for incoming download
Small fix on incoming download & doku

Thread starting problem on resume
Remove Runnable interface from incoming download

Hides the fact that the IncomingDownload implements runnable. Others could start an instance as a Thread which could lead to incosistent states
Add test for outgoing filelist transfer + fix
Combine OutgoingFilelist- and OutgoingFileTransfer

closes issue #18
manual merge