New - Repeating FixDateProvider
Dependency Management & test-base project

Cleaned up POMs, introduced dependency management and introduced a
test-base project.
OPEN - task 5: Model billing system 

Created a cleaner test for the bill formatter.

https://github.com/BernhardBln/opensourcecashregister/issues/issue/5
Shrunk interface - less public methods
Unittest & SpringConfig

Fixed broken integration test and renamed spring context to emphasise
that it does a compontent scan (which finds and imports other config
classes)
double fix for multiple bill reprint

* Wrong action listener would call "setBillToGo" way too often.

* SetGlobalTaxInfo in billService did not check if the taxInfo has
actually changed before setting and firing the change event. That also
needed to be fixed for other methods in there.
Deleted empty and defective test
Another fix for data storage test