Backuptool update.

 - No need to backup the msig folder, as keys are saved in the
   gpg keyring. Just backing up the db/ folder.
 - I, Angel Leon, I'm the original author of this file and I
   remove the GPL header block so that other open source license
   can be applied to this file, preferably the MIT license,
   as described on the LICENSE.txt file of the OpenBazaar project.
 - pep8 fixes.