add test coverage for EventFactory
add test coverage for BlockedEvent
add test coverage for OpenEvent
fix bug in OpenEvent getters
add test coverage for BounceEvent
add test coverage for ClickEvent
fix wrong event test types
add test coverage for SpamEvent
add test coverage for TypofixEvent
add test coverage for UnsubEvent
add test coverage for Client connection mode, output format methods
open up lower level API (mainly for testing purposes, but could also serve for overriding)
test Client bogus get/post queries
[WIP] add test coverage for Client::get
add travis config