Fix: https://github.com/cappuccino/cappuccino/pull/2158

Further work had to be done on this issue due to Firefox not liking the IE11 fix.  I've isolated the IE fix for only IE browsers.  CFHTTPRequest now takes an "isIE" flag to decide whether to set withCredentials before (not IE) or after (IE) opening the XMLHTTPRequest.

Refs: #2157