Refactor code to separate Model from Controller

* Note handling functions moved to a new class in a separate file.
* secure_remove tweaked to remove all existing files in one call.
More separation changes

* Moved file checks from controller to the model
* Simplified HMAC digest comparison
* Simplified data dir specification to make for easier moves.
Moved utility functions to utils.py
	modified:   note.py

HMAC comparison should be done before we attempt to uncompress, otherwise we
have a timing attack.

Additionally HMAC comparison should be done in constant time, again to prevent
timing attacks.

See http://codahale.com/a-lesson-in-timing-attacks/ for example.
Stupid typo
Merge pull request #31 from atoponce/refactor

Refactor code to separate Model from Controller. note.py created for handling the note work, and utils.py for external utility functions for various operations.
fix typo in faq
add debuging back to __init__.py
Merge branch 'master' of github.com:atoponce/d-note