Added Request::toArray() method, toString() now return json encoded result of toArray()
Added Util::convertRequestToCurlCommand() method

Conflicts:
	lib/Elastica/Util.php
	test/lib/Elastica/UtilTest.php
Set Request into ResponseException

Conflicts:
	lib/Elastica/Exception/Response.php
	lib/Elastica/Transport/Http.php
	lib/Elastica/Transport/Memcache.php
	lib/Elastica/Transport/Thrift.php