test($httpBackend): add test for using ActiveXObject in IE8 for PATCH operations

In Internet Explorer 8, the native XMLHttpRequest object does not allow the
HTTP PATCH method. This tests that in IE8, when performing a PATCH, we fall
back to ActiveXObject.
fix($httpBackend): fix HTTP PATCH requests in IE8

In Internet Explorer 8, the native XMLHttpRequest object does not allow the
HTTP PATCH method. In order to accomplish a PATCH, you need to use the ActiveX
object. Update the default XHR to use the ActiveX object when doing a PATCH in
IE8. See the following for documentation:

http://blogs.msdn.com/b/ieinternals/archive/2009/07/23/the-ie8-native-xmlhttprequest-object.aspx
http://bugs.jquery.com/ticket/13240