Updating client to be compliant with RFC 2616: case-insensitive headers

[douglasmiller]

According to section 4.2 of RFC 2616:

Each header field consists of a name followed by a colon (":") and the field value. Field names are case-insensitive.

This update will make the client treat headers in a case-insensitive manner.

[joannasese]

ref: refs/heads/2-5-headers
PHP 5.3.29 (cli) (built: Oct 9 2014 00:21:49)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2014 Zend Technologies
PHPUnit 4.2.6 by Sebastian Bergmann.

Configuration read from /app/phpunit.xml.dist

............................................................... 63 / 105 ( 60%)
..........................................

Time: 3.04 seconds, Memory: 13.75MB

OK (105 tests, 405 assertions)

---

ref: refs/heads/2-5-headers
PHP 5.5.38 (cli) (built: Aug 10 2016 20:52:31)
Copyright (c) 1997-2015 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2015 Zend Technologies
PHPUnit 4.2.6 by Sebastian Bergmann.

Configuration read from /app/phpunit.xml.dist

............................................................... 63 / 105 ( 60%)
..........................................

Time: 1.66 seconds, Memory: 9.25MB

OK (105 tests, 405 assertions)

[joannasese]

PHP 5.3 and 5.5 tests are passing. 👍