[INTERNAL] removed unused method from SPathDataObject

The getPath method was only used by one activity. Furthermore
the method of this activity was also no used. 

Removed the method which should help to create a better platform
independent way of serializing those SPath objects.

Change-Id: I14a80fe2450c842b096ca474d581334c12861609
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1379
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>