Added abstract ContainerHolder, implemented it in Transporter and Agv
Added documentation to Transporter
Added Storage class
Replaced setter statement with setter method
Added unit testing for Storage
Implemented ContainerHolder in Storage
Moved Container to models
Merge pull request #16 from Rubykuby/containermodel

Moved Container to models
Added getArrivalDate & getDepartureDate to container
Merge branch 'date'
Merge branch 'containerholder'

Conflicts:
	src/main/java/org/nhl/containing_backend/vehicles/Agv.java
	src/test/java/org/nhl/containing_backend/vehicles/TestAgv.java
Hotfix for Container imports