Use NOVA_BIN_DIR for newer binaries.

We added a variable a while ago, NOVA_BIN_DIR which is set properly to the
location of the binaries. Rather than using the in-tree bin-dir, which is
going away in favor of entrypoints console_scripts.

Change-Id: I65040cfe8321d49595a909353870f981bbd6a480
diff --git a/lib/nova b/lib/nova
index b5efce9..3ea2f2a 100644
--- a/lib/nova
+++ b/lib/nova
@@ -432,9 +432,9 @@
     screen_it n-net "cd $NOVA_DIR && $NOVA_BIN_DIR/nova-network"
     screen_it n-sch "cd $NOVA_DIR && $NOVA_BIN_DIR/nova-scheduler"
     screen_it n-novnc "cd $NOVNC_DIR && ./utils/nova-novncproxy --config-file $NOVA_CONF --web ."
-    screen_it n-xvnc "cd $NOVA_DIR && ./bin/nova-xvpvncproxy --config-file $NOVA_CONF"
-    screen_it n-cauth "cd $NOVA_DIR && ./bin/nova-consoleauth"
-    screen_it n-cond "cd $NOVA_DIR && ./bin/nova-conductor"
+    screen_it n-xvnc "cd $NOVA_DIR && $NOVA_BIN_DIR/nova-xvpvncproxy --config-file $NOVA_CONF"
+    screen_it n-cauth "cd $NOVA_DIR && $NOVA_BIN_DIR/nova-consoleauth"
+    screen_it n-cond "cd $NOVA_DIR && $NOVA_BIN_DIR/nova-conductor"
 }
 
 # stop_nova() - Stop running processes (non-screen)