Merging Envoy Fixes from https://github.com/kaizensparc/pbjson

Hey;
I was wondering if you would accept a PR to merge envoy fixes from https://github.com/kaizensparc/pbjson and branch "fix-envoy"?
This has some code to fix envoy's specific serialization/deserialization with "any" types.

Start by reviewing the referenced kaizensparc/pbjson repository and its fix-envoy branch, then compare the Envoy-specific serialization and deserialization changes with this project. Done means determining whether those fixes can be merged into influxdata/pbjson and validating the result for Envoy's any types.

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