Invalid swagger generated for bodies with repeated fields

[johanbrandhorst]

As reported in #902 (comment), it appears #902 means we're generating invalid swagger definitions for some methods which take repeated fields as parameters. I think this is only affecting fields which have a repeated field in the body of the request as opposed to in the URL query parameters, so we may need some extra logic in the swagger generator to only set the collection format when we know the parameters are going into the URL query parameters.

[johanbrandhorst]

Closing in favour of #756