Updates to make basePath work with current swaggerui

The current swaggerui doesn't work with swagger-express if the basePath is left out, so I made it not optional.

The endpoints that were serving the swagger json were also pointing to the wrong place for the current swaggerui. The current swaggerui prepends the part of the basePath after the host to what is set as swaggerJSON, so I just updated the regex to also include that part of the basePath.

I also set the version of express used since the current example app is incompatible with express 4.0.0.