added a -p option to mkdir .heroku it is safer incase .heroku is already...

added a -p option to mkdir .heroku it is safer incase .heroku is already created, it won't error out

bin/compile

@@ -56,7 +56,7 @@ echo "-----> Preparing virtualenv version $(virtualenv --version)"
 virtualenv --no-site-packages . | indent
 
 # create set-aside .heroku folder.
-mkdir .heroku
+mkdir -p .heroku
 
 
 # if pylibmc within requirements, use vendored libmemcached