don't set contentType for empty body

When content-type is set to a non-standard value,
CORS requires a preflight request that needs to be handled
by the destination server.
We shouldn't require that, when no body is sent at all
and the content-type is irrelevant anyways.
updated to support file + form params in same request
Merge branch 'master' of github.com:wordnik/swagger-ui
Making fonts call protocol agnostic so it works behind https
Merge pull request #179 from paulhill/master

Making fonts call protocol agnostic so it works behind https
Merge pull request #166 from JonnyJD/simpler-cors

don't set contentType for empty body
fix for sending content-type header during GET requests