Use gogo protobuf as the protoc compiler

[prestonvanloon]

Includes #1149 (already merged)

There are many benefits to gogo protobuf including:

• fast marshalling and unmarshalling
• more canonical Go structures
• goprotobuf compatibility
• less typing by optionally generating extra helper code
• peace of mind by optionally generating test and benchmark code
• other serialization formats

See more here:
github.com/gogo/protobuf

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@b9a233d). Click here to learn what that means.
The diff coverage is 72.35%.

@@            Coverage Diff            @@
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  Hits              ?     3713           
  Misses            ?     1080           
  Partials          ?      324

[terencechain]

lgtm, thanks for doing this!