Merge pull request #36 from broggi/master

Implemented ExpandableListView
added some tests, changed item- and shoppinglisthandler
Merge pull request #37 from marcSchneiter/master

added some tests, changed item- and shoppinglisthandler
Continued work on ExpandableListView

Items are shown if there are 5 or less to be bought, otherwise the list
shows up as normal list