Re-work asset cache descriptor files to not appear in source control when working

[Pysis868]

Right now when I am working on anything in the project repo and want to check in some files, I always see timestamp changes for the css.ini and javascript.ini files, and don't want them to appear when I have no needed changes for them.

They are currently ignored, but since they have been committed before, they still appear when changes are made automatically by the server caching system.

I believe this is because the file serves 2 purposes. One to initially list the files that should be included, and another to finally track which version of the files have been compiled.

Maybe this way their functionality could be split into separate files for more granular control in SCM.

[Pysis868]

Implemented by #311.