Kill all swift processes before trying to install.

- Before trying to install swift we ensure there is no swift processes
  running.

Change-Id: Ibeb511a67f1ccc4914d9cdf2874324159e3928cc
diff --git a/stack.sh b/stack.sh
index 87d38d2..0955b1d 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1371,6 +1371,9 @@
     # Install memcached for swift.
     install_package memcached
 
+    # We make sure to kill all swift processes first
+    pkill -f -9 swift-
+
     # We first do a bit of setup by creating the directories and
     # changing the permissions so we can run it as our user.