allow to append to cache output
store the file name in the cache for later retrieval
get cache key instead of file name
Revert "get cache key instead of file name"

This reverts commit 88e0171757b27f17fba66ec0aff91a784f29c727.
add cache flags, constants
initial js/css consolidation code

not yet ready for admin/preview
do not use in production
first working consolidation for admin resources.

still needs better cache key (not dependant on whole resource includer state but only the state of the resources actually included in the currently cached consolidation file)
Cache resource consolidation by resource, not by configuration
Merge branch 'consolidate-resources'

* consolidate-resources:
  Cache resource consolidation by resource, not by configuration
  first working consolidation for admin resources.
  initial js/css consolidation code
  add cache flags, constants
  Revert "get cache key instead of file name"
  get cache key instead of file name
  store the file name in the cache for later retrieval
  allow to append to cache output
Fix files referenced from consolidated CSS

File-relative references like ../images/test.png now
work when consolidating resources.

This should conclude most of the work done in the consolidate_resources branch