build: Remove player module
build: Add connman page

Replaces network manager page with connman
assistant-gd: Disconnect visible-child signal on dispose

This signal gets fired on closing gnome-initial-setup but the page has
been disposed by this time so update_action_widget causes a segfault.
connman: Hack to fix grab issue
build: Fix race on generated file when parallel building
connman: Add service checks to make sure we don't crash on a non item