Changed access modifier for the function getQRText() from private to
public.
This allows for generating the QR Code in different ways (eg pass the
data from getQRText() to the client and have a Javascript Library render
the QR Code)
* Added a bunch basic of unittests for the RNG's
* QRicketProvider and QRServerProvider now throw on invalid MIME-types
* TwoFactorAuth now first tries to use CSRNGProvider before any of the other RNG providers
Jonathan Trummer
RobThree