Ansible: Add X.org configuration

- Detect if X.org is installed with a small fact script
- Symlink Xdefaults file if X.org is installed

Ansible/facts/xorg.fact

@@ -0,0 +1,9 @@
+#!/usr/bin/env zsh
+
+if which xorg 1>/dev/null 2>&1; then
+    xorg_exists="true"
+else
+    xorg_exists="false"
+fi
+
+echo "{ \"exists\": ${xorg_exists} }"