Add instructions for and allow dumping profiles to files in production. Refs #1
Rendering to file improvements:

* Prevent rendering other unwanted blocks from layout.
* Fix rendering when in adminhtml.
* Make target path configurable.
* Add microseconds to filename to prevent collisions.
* Add title override.
Error-check directory creation and file writing.
Manually merged 79c62f544c8132d9cfb9bebf576edc8fdde7c97b