delete cinder configuration file before config it

Some misleading configuration item will remain if we don't delete the cinder
conf everytime before we configure it.

Change-Id: Iab6a5d7bc5fdcb05b28d24b0419c0bf380a140c1
Closes-bug: #1405301
diff --git a/lib/cinder b/lib/cinder
index c106424..3e8ed53 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -205,6 +205,8 @@
 
     cp -p $CINDER_DIR/etc/cinder/policy.json $CINDER_CONF_DIR
 
+    rm -f $CINDER_CONF
+
     configure_cinder_rootwrap
 
     cp $CINDER_DIR/etc/cinder/api-paste.ini $CINDER_API_PASTE_INI