Refactor App Handlers

This PR refactors the AppHandlers code and related tests. Its intent is to speed up the necessary tests and remove the unwanted ones (~1,300 loc). The changes to the library are minor and should retain all prior functionality.

Changes:
- Clean up formatting of source
- Remove unnecessary tests
- Add new appropriate tests
- Rename test sections to be more clear
- Speed up tests

There are also a few minor additional changes. They are:

Additional:
- Moved preamble to header template
- Simplified `F2.log()` function

Please double check my changes to `src/lib/app_handlers.js` and `F2.log()` to make sure I didn't alter existing functionality. Also, if possible, please pull down this branch and look over the AppHandler tests. See if there's anything missing or if any of the test cases should be moved around.