implemented shm/ramdisk supports for GPG ops https://github.com/globaleaks/GlobaLeaks/issues/283
supported encrypted file status and download: https://github.com/globaleaks/GlobaLeaks/issues/187
enhanced and refactored a core part of migration script:

        _   _         _  _          _   __ _
       | | | |  ___  | || |  ___   | | / /(_)  _     _
       | |_| | / _ \ | || | / _ \  | |/ /  _ _| |_ _| |_  _  _
       |  _  |/ /_\ \| || |/ / \ \ |   /  | |_   _|_   _|| |/ /
       | | | |\ ,___/| || |\ \_/ / | |\ \ | | | |_  | |_ | / /
       |_| |_| \___/ |_||_| \___/  |_| \_\|_| \___| \___||  /
                              _           _              / /
                             / \_______ /|_\             \/
                            /          /_/ \__
                           /             \_/ /
                         _|_              |/|_
                         _|_  O    _    O  _|_
                         _|_      (_)      _|_
                          \                 /
                           _\_____________/_
                          /  \/  (___)  \/  \
                          \__(  o     o  )__/    w/ StormSQLHell!
Merge branch 'devel' of github.com:globaleaks/GLBackend into devel