added basic Participant.java
added basic Workshop.java
added import for Date in Workshop.java
added basic Speaker.java
added basic Event.java
enhanced Workshop.java (getter, methods)

added attend and getter methods
enhanced Event.java (getter, methods)

added attend and getter methods
enhanced Participant.java (getter)
enhanced Speaker.java (getter)
added MobileGamesHacker for testing
MobileGamesHacker: further testing
added class diagramm