ZF-2229: ZCResponse::getHeader() should be case-insensitive
Zend_Controller_Response_Abstract::getHeader() is case-sensitive whereas it is stated in the http rfc that header field names are case insensitive.
the two following call should return the same:
see http://w3.org/Protocols/rfc2616/… for reference
"Each header field consists of a name followed by a colon (":") and the field value. Field names are case-insensitive."