[API] method removeFirstSegments() added to IPath

Change-Id: I0f6144c646edf7d29f1e253d4091b6d7b6f17250
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1694
Tested-by: Jenkins CI
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>