Support delete method in swagger generator

[beerose]

Solves #559 and generates query parameters for the delete method.

[tmc]

Thanks for your contribution! The upstream issue appears fixed, can you rebase to trigger another build?

[yugui]

https://travis-ci.org/grpc-ecosystem/grpc-gateway/jobs/370802179 (Go 1.10.x; GATEWAY_PLUGIN_FLAGS=) is failing due to the issue solved by #619.
https://travis-ci.org/grpc-ecosystem/grpc-gateway/jobs/370802182 (Go master; GATEWAY_PLUGIN_FLAGS=request_context=false) seems to be flaky. And now failing because of incompatibility to #618.

Would you mind rebasing the branch again?

[yugui]

Confirmed in https://travis-ci.org/grpc-ecosystem/grpc-gateway/builds/370873461. The branch is safe to merge.

I can merge this PR if it looks good to @achew22.

[codecov-io]

Codecov Report

Merging #616 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #616   +/-   ##
=======================================
  Coverage   59.28%   59.28%           
=======================================
  Files          28       28           
  Lines        2780     2780           
=======================================
  Hits         1648     1648           
  Misses        971      971           
  Partials      161      161

Impacted Files	Coverage Δ
protoc-gen-swagger/genswagger/template.go	42.35% <100%> (ø)	⬆️

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[beerose]

@yugui done 🙂

[achew22]

Can you change one of the proto files to exhibit this new behavior and run make examples?

[beerose]

I've added simple endpoint exhibiting the new behavior to the examples @achew22

[achew22]

@BlackDahila, I think this is good to go. Thanks so much for your contribution! I look forward to doing it again soon.