Clear out the keystone pki data for each run

This prevents old invalid tokens from working after a rerun of stack.sh
and potentially providing users and tenants that don't exist.

Fixes bug 1089700

Change-Id: Icfc22978e41e459d51b50bc7ad2e6d98d766e402
diff --git a/lib/glance b/lib/glance
index 4f631b2..8ba04b3 100644
--- a/lib/glance
+++ b/lib/glance
@@ -162,8 +162,10 @@
     # Create cache dir
     sudo mkdir -p $GLANCE_AUTH_CACHE_DIR/api
     sudo chown `whoami` $GLANCE_AUTH_CACHE_DIR/api
+    rm -f $GLANCE_AUTH_CACHE_DIR/api/*
     sudo mkdir -p $GLANCE_AUTH_CACHE_DIR/registry
     sudo chown `whoami` $GLANCE_AUTH_CACHE_DIR/registry
+    rm -f $GLANCE_AUTH_CACHE_DIR/registry/*
 }
 
 # install_glanceclient() - Collect source and prepare