Merge pull request #1 from nulab/master

fetch upstream
bugfix() http://tools.ietf.org/html/rfc6749#section-5.1

The authorization server MUST include the HTTP "Cache-Control"
   response header field [RFC2616] with a value of "no-store" in any
   response containing tokens, credentials, or other sensitive
   information, as well as the "Pragma" response header field [RFC2616]
   with a value of "no-cache".
Merge pull request #14 from centraldesktop/bugfix/rfc6749-section5.1

Add additional cache control headers per RFC 6749 Section 5.1