- Added rotation stability, now the Z-Axes always points verticaly
independent of the phone position
- the basic framework for the Potthole Detection is done
 - combines GPS-Position with Accelerometer Data
 - A list shows detected pottholes
 - plays sound on a detection

sidenote: the rotation invariance seems to be unstable (every movement
throws it off enough, so that the z-axis isn't accurate anymore)