Update actionpack, activerecord, nokogiri gems
Update actionpack, activerecord, nokogiri gems

Ran `bundle update actionpack activerecord nokogiri rails` to mitigate:
* [CVE-2016-2098](https://groups.google.com/forum/#!topic/ruby-security-ann/ly-IH-fxr_Q)
* [CVE-2016-6317](https://groups.google.com/forum/#!topic/rubyonrails-security/rgO20zYW33s)
* [CVE-2015-8806](https://github.com/sparklemotion/nokogiri/issues/1473)

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