[FEATURE] Speedup backend and allow compression in frontend

This patch improves the determination of relative paths of include
files, concatenates the jsFiles and jsFooterFiles in backend by
default to speedup the backend and provides a default compressor
for the frontend.

Change-Id: I569d285cc12c7eec808094903d5c8ee2e749f9ec
Resolves: #27694
Reviewed-on: http://review.typo3.org/2924
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind
Reviewed-by: Steffen Gebert
Tested-by: Steffen Gebert
Reviewed-by: Georg Ringer