theme_text_color updated to theme_fg_color

There is no theme_text_color in Gtk 3.14, this
results  in dark-on-dark unreadable widgets using
Adwaita dark variant.

text_color is equal to fg_color in Gtk 3.6, so the
dependency has been increased.

See: https://bugzilla.gnome.org/show_bug.cgi?id=737340
Moved all the encryption stuff to the SQLiteVFS

In another step to complete our own SQLiteVFS, the coded that
encrypt/decrypt the database has been moved from StorageManager to the
VFS.

It was required to adapt some APIs and make the call to gpgme_wait in a
blocker way, due it's required to end the encryption before to close the
application.

See Bug #659500 - Prevent the unencrypted database from hitting the disk
https://bugzilla.gnome.org/show_bug.cgi?id=659500
Updated POTFILES.in
Updated Polish translation
Updated Indonesian translation
Updated Brazilian Portuguese translation
Updated Serbian translation
Updated Czech translation