Provide a mechnism to disable the caching

[squareplanetdesign]

I am working on a plugin to requirejs and really wanted to write my unit tests using this tool. However, the caching behavior prevents me from writing tests for the variations that my requirejs plugin is trying to test without breaking every single test into a completely independent Karma.config file.

It would be nice to have a switch that allowed me to have all the tests in one file and run with independent requirejs caches which I think would be the behavior if there was a way to disable the caching you added.

If you have other ideas about how I could setup these test or want to see how the plugin testing kind of works: https://github.com/squareplanetdesign/requirejs-min-plugin..... I would appreciate any suggestions you may have if disabling the caching is not the best approach.