Inserted new Navigation
Merge pull request #11 from tendlich/master

Inserted new Navigation
Cleaned up the Overviewer activity and put Overviewer's Listadapter in a
extra class file. Implemented a prototype to show a list of spare parts
and scan them after selecting a repair order.
Lost by the last commit (4373b8f8f251c617f9cb85bafa797bc77165454b)
Merge#12
Up and down navigation fixed in "Overviewer" list
Method added to the bike data controller which returns a list of compatible components ffor a specific bike