moved category details into fragment, some refactoring
fixed layout reference for large screens
two-column layout for landscape orientation in category overview
fragment
added margins to some layouts
fixed NPE on orientation change when trying to save instance state
optimized data parsing (reduced memory usage)
fixed error in Dropbox authenticating
optimized IndicatorView drawing for scaling
scrolling can be programmatically enabled/disabled in ScrollabeChartView
replaced some integers by floats
removed unnessessary constants
added missing click listener at large-screen listview, minor fixes
organized category overview activity in actionbar tabs
added tabs with single full size view from category overview