[NOJIRA] Response to some strange png requests against boostrap#index

While combing through the logs:
- Noticed that the .ico file wasn't resolving, we're pointing to a 0 byte file in /public? I redirected this towards the /assets/favicon.ico using the rails erb tag helpers.
- This one's a bizarre one that i can't understand how it comes through in the qa logs, there's lots of these entries:

[2013-05-14 14:39:43] [INFO] [CalCentral] Processing by BootstrapController#index as PNG
[2013-05-14 14:39:43] [INFO] [CalCentral]   Parameters: {"url"=>"assets/calcentral_logo_pilot_text"}

Doesn't make any sense, calcentral_logo_pilot_text.png doesn't even exist anywhere in our codebase anymore, and in addition we're not checking on bootstrap#index against non-html requests and just attempting to return the standard bootstrap pages. I wrapped the routes with defaults and the controller with some respond_to calls so that it will only respond to html page requests for things falling into the default route. Other request will get a friendly 406 response.