1072285 django upgrade

This upgrades Input to django 1.6.8. It also upgrades to django-adminplus v0.3 and updates django-nose and django-cache-machine to master tip.

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I tweaked this because I saw it in a blog post, but I didn't look into whether it was substantially different than `cache.clear()`. It did seem more explicit and if I ever have multiple caches, it's nice to know which ones are getting cleared.