apman: add support for ConmanDebug experiment.

This is registered by the conman init script (S52conman) and already
supported by conman internally.

Change-Id: I412008fc5f3ff520a9775fc5a3c84848d0433b91
diff --git a/fs/skeleton/bin/apman b/fs/skeleton/bin/apman
index 8466304..8780a94 100755
--- a/fs/skeleton/bin/apman
+++ b/fs/skeleton/bin/apman
@@ -13,6 +13,10 @@
   initrwnd=
 fi
 
+if experiment ConmanDebug; then
+  set -x
+fi
+
 TMP_DIR="/tmp/conman"
 CONFIG_DIR="/config/conman"