Merge pull request #222 from mattbrictson/patch-1

Remove ensure_security_headers for 3.x upgrade

Author: oreoshake

upgrading-to-3-0.md

@@ -20,6 +20,7 @@ Migrating to 3.x from <= 2.x
 1. Convert all instances of `self`/`none`/`eval`/`inline` to the corresponding values in the above table.
 1. Convert all CSP space-delimited directives to an array of strings.
 1. Convert all `enforce: true|false` to `report_only: true|false`. 
+1. Remove `ensure_security_headers` from controllers (3.x uses a middleware instead).
 
 Everything is terrible, why should I upgrade?
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