nova: Use noVNC 1.3.0 when installing from source

Additionally make the repo name lowercase to match the project name in
our zuul config so that jobs can check the repo out.

Change-Id: Ic2d9c4fa837461bbc29e067a81912b5f72efd3ca
diff --git a/lib/nova b/lib/nova
index 9aae2c4..3460c21 100644
--- a/lib/nova
+++ b/lib/nova
@@ -831,7 +831,7 @@
             NOVNC_WEB_DIR=/usr/share/novnc
             install_package novnc
         else
-            NOVNC_WEB_DIR=$DEST/noVNC
+            NOVNC_WEB_DIR=$DEST/novnc
             git_clone $NOVNC_REPO $NOVNC_WEB_DIR $NOVNC_BRANCH
         fi
     fi