Fix testing errors in WS bearer token external system

I don't know if the WS bearer token external system is fully functional, but I was using it as a quick test for http client functions. Some issues with testing:

• Not setting a URL for the test
• If GET fails, tries to match regex with null, givine NPE
• UI calling GuiScreenAction.newMessage() not GuiScreenAction.newMessageAppend(), so is only showing the last error in a list