Verify correctness of endpoints with file parameters

[yelp]

Verify correctness of endpoints with file parameters

[macisamuele]

I do have some conclusive results over here.
I'm currently preparing a PR to address the issue and to write the missing tests of #90 .

According to the swagger specifications in order to send files the operation must consume multipart/form-data (doc). The junit-tests file endpoint does not define multipart/form-data and so the generate code does not work well.

Considering this we have two alternatives:

1. Find a way to make it work anyway
2. Stick to the swagger specifications and annotate the endpoint as unsafe so we will discourage usage of the endpoint.

I'm aiming to use the second alternative