Issue  #2 - Configure transport responsible for serialization of event to json

Renamed method argument

Changed configuring of the event transport

Added description for the EventTransport

Changed serialization/deserialization of events using I/O Streams

Added contract test for testing serialization of async events

Updated version of gson and guava libraries
Configured encoding when serializing events
Updated to AppEngine 1.9.2
Updated to AppEngine v1.9.4
Updated AppEngine version to 1.9.8