Ability to not log every request, optimizations, db_index, and a management command

Hope this is helpful.

* adds a setting to not log every request, which makes this easier to use on a high-load site
* use Python's cProfile class to profile all method calls in a request (with a setting to turn it on)
* adds a management command to clear the request/response/etc. tables

and

* doesn't compute a reverse or load the configuration on every request
* adds some indexes to the models
* tweaks templates, README
* on the SQL queries page, display the query start time as relative to the request start time