ContactEditor: update has_nickname_row properly

Removed hack. This code can still be improved but that will come
eventually, when we implement inline contact creation
build: bumping Gtk+ and Vala version

This is bumped farther from the one suggested in the bug because I'm
using Gtk+ features from newr releases.

Fixed: https://bugzilla.gnome.org/show_bug.cgi?id=727584