Improve PascalFromSnake behavior

[tmc]

Fixes #84 (and doesn't bring in new dependency)

[yugui]

Could you add the following copyright notice as a comment just after this line?

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[yugui]

Thank you for your contribution.
LGTM as a short-term solution except the license issue I commented above.

For mid-term, it might be better to generate static mapping between proto field names and go field names because the only runtime usage of PascalFromSnake is in runtime/query.go. So once we have the static mapping for runtime usage, we can safely depend on "github.com/golang/protobuf/protoc-gen-go/generator".CamelCase.

The test failure in Travis CI is caused because generated files in the repository are out-of-date. So you can ignore the failure for now.

[tmc]

@yugui I like that solution for the mid-term.

[yugui]

LGTM

[yugui]

Thank you!