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.

[douglasmiller]

└[$]› php all_tests.php
all_tests.php
OK
Test cases run: 9/9, Passes: 71, Failures: 0, Exceptions: 0

[dbrudner]

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
all_tests.php
OK
Test cases run: 9/9, Passes: 71, Failures: 0, Exceptions: 0

PHP 5.4.45 (cli) (built: Dec  5 2015 08:26:46) 
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies
all_tests.php
OK
Test cases run: 9/9, Passes: 71, Failures: 0, Exceptions: 0

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
all_tests.php
OK
Test cases run: 9/9, Passes: 71, Failures: 0, Exceptions: 0