web: TotpAuthenticator: Added new method to specify image size in
generated barcode url.
web: TotpAuthenticator: Incremented secret size to 20 bytes as 10 are to
unsecure.
web: TotpAuthenticator: Dont add request context to qrcode url
web: TotpAuthenticator: secret key size back to default as there might
be persistence model changes needed. new method to specify secret key
length added.