Update CHANGELOG for 0.2.6 release
Update CHANGELOG for 0.2.6 release

camlow325/clj-http-client,rlinehan/clj-http-client,scottyw/clj-http-client,camlow325/clj-http-client,rlinehan/clj-http-client,scottyw/clj-http-client,puppetlabs/clj-http-client,dmcpl/clj-http-client,puppetlabs/clj-http-client,dmcpl/clj-http-client