Author: Simey Lameze
MDL-59142 core_theme: cache post-processed css
Thanks Cameron Ball for the base patch
http://git.moodle.org/gw?p=moodle.git;a=commit;h=4cc2f33b08f3294e7aa59c2de2ee6bc48ced2a91
http://github.com/moodle/moodle/commit/4cc2f33b08f3294e7aa59c2de2ee6bc48ced2a91
+ 3.4 en [cachedef_postprocessedcss,core_cache]