allow interceptors to be parsed as js functions UPDATED

[Dsolnik]

This provides an alternative approach to adding swagger ui function parameters that supports older browsers.

I took the code from #35 written by @carlosreif and made some updates so that it would be able to support older browsers.

To pass a function parameter, the requester must be sure to name the function the same as the name of the parameter.

i.e.

get_swagger_ui_blueprint(prefix, url, config={'requestInterceptor':'function requestInterceptor(req){}'})