[#2369] [GTKUI] Fix bypassing tray password dialog

Created a generic password dialog and moved the unlock code out of
systemtray so any call to window.present will now show the dialog.

Also fixed the appindicator not showing the correct visible status
[GTKUI] Fix quitting bypassing password lock
[GTKUI] Typo causing password dialog to show
[#2315] [GTKUI] Potential fix for lost window on Win32
Prevent private flagged torrents auto-merging trackers

When adding a torrent already in session any new trackers are merged
to the exiting torrent but this is an unwanted feature for private
flagged torrents.
[#2418] Fix WebUI error when adding non-ascii torrent

json.dumps attempts to decode (utf8) the 'path' entry which had a
different encoding. The solution is to ensure the 'path' entry is
utf8 encoded and remove the unneeded 'path.utf-8' entry.

As self.__m_metadata["info"]["files"] is updated the later code
checking and decoding the 'path' entry can be removed.
[GTKUI] Fix text typo and mark for translation
Update translation po files from launchpad
Update POT file
Update ChangeLog
[WebUI] Update compressed js
Bump version to 1.3.7
Merge pull request #4 from deluge-torrent/1.3-stable

1.3 stable