Code refactoring: deleted some unnecessary code.
Made the validation of the scanned barcode more robust.

Also some more code refactoring.
Fixed wrong use of file open
Sections: First attempt to write emails

This fails for now as there bugs somewhere else, i.e. fopen
being used.
We have to merge a better working version.
Merge commit '5abe5c443bb90e86b1bcf3c9e46a9fdca9ed70a1' into email

for the fopen fix

Conflicts:
	Sections.py
	    meh, the change made on the email branch looks bigger than it is
Sections: Using the proper filename of the signed key and a real UID

This makes it send emails.
Well, it opens the email client of the user. Testing with Evolution.
It will be interesting to see how it will react when non-email-address UIDs will
be handled.

So far, subject and body are missing.
Sections: Introducing a subject and a body
temporary commit, encryption doesn't seem to work