Fix for base path "/"

This fixes a problem I had with with the relative base path "/".
My swagger setup is the following:
`http://localhost:8080/core/api-docs/` <- hosts the "main" api doc:
```
{
  "apiVersion" : "v2",
  "swaggerVersion" : "1.2",
  "apis" : [ {
    "path" : "/api/2.0/report.{format}",
    "description" : "Get reports"
  } ]
}
```
`http://localhost:8080/core/api-docs/api/2.0/report.json` <- hosts the actual api doc (for this example it's on the same server but actually it is be hosted elsewhere)
```
{
  "apiVersion" : "2.0",
  "swaggerVersion" : "1.2",
  "basePath" : "/",
  "resourcePath" : "/api/2.0/report",
  "apis" : [ {
    "path" : "/api/2.0/report/{id}",
    "operations" : [ {
      "method" : "GET",
      "summary" : "Fetch report data",
            ...
  } ]
}
```
Now, what I'd expect when i try out the "Fetch report data" endpoint, is for the URL to be the base path of the server the api documentation is on + the resource path. 
What actually happens (before this pull request) is that I get a request for 
`http://localhost:8080/core/api-docs/api/2.0/report/`, clearly not what i want! 
With this fix, the url is 
`http://localhost:8080/api/2.0/report/` as expected.

Hope you can understand this, I have to admit the different types of paths confuses me a bit but I'm pretty sure this is the way its supposed to work! :)