rename CachingExtensions to Rails, to match the class it overrides

Change-Id: Iab255ac1fd7f45cae7db070c4d6f70368697b7e2
Reviewed-on: https://gerrit.instructure.com/31670
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
fix cache namespacing for caches created outside of switchman's control

Change-Id: I8e12983b4cd0feb622f9f1c91edf09181d0eb131
Reviewed-on: https://gerrit.instructure.com/31698
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>