Check's attributes not escaped properly

[goblin]

If your noit check contains xml-unsafe characters like < or > (which can easily occur in http body checks), it all breaks:

<?xml version="1.0" encoding="utf8"?>
<error>xml parse error</error>

That's because they're not escaped at https://github.com/thommay/hobelar/blob/master/lib/hobelar.rb#L41

I tried to fix it by writing a test first (even though there aren't any tests yet), but it appears that WebMock is broken too: bblimke/webmock#217