Updated Russian translation
po/vi: import from Damned Lies
Updated Vietnamese translation
Updated Lithunian translation
Updated Greek translation
prefs: Don't show preferences when no preferences are available

If seahorse is built without GnuPG support (not recommended, but
possible) then there are currently no preferences available.

Hide the Preferences menu item in these cases, so it doesn't show
a confusing empty window.

In addition fix some assertions and cleanup some unused code
related to this.

https://bugzilla.gnome.org/show_bug.cgi?id=694678
pgp: Fix build issues with prefs refactoring
Release version 3.7.91
[l10n] Updated German translation
pgp: Fix build when --without-ldap or --without-hkp

Having so many optional dependencies is rather dubious. Let's not
add more carelessly. But fixing the build in the interim makes sense.
Assamese translation updated for gnome 3.8
Updated Belarusian translation.
update Simplified Chinese (zh_CN) translation
Finnish translation update by Jiri Grönroos
[l10n] Updated Catalan translation
Updated Portuguese translation and converted to New Spelling (Novo AO)
[l10n] Updated Estonian translation
Updated Galician translations for docs
Updated Hungarian translation
Updated Danish translation