Update pear-HTTP_Request2 to 2.3.0.

2.3.0.

New features:

* New observer that can do on-the-fly decoding of compressed responses,
  see HTTP_Request2_Observer_UncompressingDownload.
  Thanks to Delian Krustev for initial implementation.

* CookieJar can now silently ignore invalid cookies with
  $jar->ignoreInvalidCookies(true); instead of throwing an exception. See
  requests #19937 and #20401

* Adapters now dispatch a new 'warning' event, e.g. in case of incomplete
  response body or broken 'chunked' encoding. Exception was thrown previously
  by Socket adapter in the latter case, see bug #20228

* Improved security of HTTPS requests in Socket adapter

  - Use 'tls://' instead of 'ssl://' in connection string to prevent fallback
    to known insecure versions, use only TLS when enabling crypto via proxy
    (see bug #20462)
  - On PHP 5.6+ require using only TLS 1.1 and TLS 1.2
  - Do not use insecure ciphers

* Improved test suite, network-backed tests now run on Travis CI

Changes and fixes:

* Curl adapter failed to send PUT request body with 'follow_redirects' on
  (bug #20440)

* Curl adapter supplied invalid cookie domain to CookieJar after redirect
  (bug #20561)

* Curl adapter now properly dispatches events while sending the request

* mime_content_type() returning false was handled incorrectly when guessing
  content-type

* Use 'peer_name' and 'verify_peer_name' SSL context options on PHP 5.6+
  instead of deprecated 'CN_match'

* Public Suffix List updated to current version, its download location changed

Note to Composer users: next package version will probably get rid of
'include-path' setting in composer.json favour of using autoloader.

(taca)