Revert "Merge branch 'master-sec'"

This reverts commit 88cc1688d0cb828c17706b41a8bd27870f2a2beb, reversing
changes made to f049016cd348627bf8db0d72382d7580bf802a79.
* Strip nils from collections on JSON and XML posts. [CVE-2013-0155] * dealing with empty hashes. Thanks Damien Mathieu

Conflicts:
	actionpack/CHANGELOG.md
	actionpack/lib/action_dispatch/http/request.rb
	actionpack/lib/action_dispatch/middleware/params_parser.rb
	activerecord/CHANGELOG.md
	activerecord/lib/active_record/relation/predicate_builder.rb
	activerecord/test/cases/relation/where_test.rb
CVE-2013-0156: Safe XML params parsing. Doesn't allow symbols or yaml.
mv README README.rdoc as app template file
remove yaml as a param parser :burn:

If you revert this commit, I will hunt you down, I will make you regret
ever terrible thing you've ever done, I will make you suffer.
Add CHANGELOG entry for YAML parsing removal

This is for commit e80546cdec56a9c3fcaf6217cba08a02d789d2bc.
Merge pull request #8827 from sikachu/master-remove-yaml-changelog

Add CHANGELOG entry for YAML parsing removal
Fix syntax error and remove duplicated test