Enable byte-range requests for all item data files. Wow, that was easy - K3 FTW!
This makes HTML5 video streaming work, and also works for Rest_Data since it
uses Controller_FileProxy for file delivery.
Move around some code blocks in Controller_FileProxy.
- disable zlib.output_compression in action_show() since also in Rest_Data.
- abort session save in action_index() since already done for REST requests.
- remove some outdated comments.
Clean up how we do cache control in Controller_FileProxy, Controller_Combined.
- remove old HTTP 1.0 headers that were confusing our otherwise 1.1 setup.
- add quotes around etags to be more careful about exact matches.
- make the etags for gzipped and non-gzipped bundles different.
Merge pull request #451 from shadlaws/fixes_20130709

Fixes 20130709