Replace \n with spaces in swagger definitions

[boosh]

Multi-line comments in .proto files are inserted into generated swagger files complete with new line characters, e.g.:

message Event {
    // Resource name, e.g. `event/{datetime}`
    // where `datetime` is an ISO date
    string name = 1;
}

will be outputted as something like:

...
"name": {
      "type": "string",
      "title": "Resource name, e.g. `event/{datetime}`\nwhere `datetime` is an ISO date"
},

It'd be neater if \n characters were replaced with spaces.

[boosh]

Actually, this is probably correct.