Allow TRUST_PROXY to pass JSON arguments to Express

[rbkreisberg]

Parse the TRUST_PROXY value as JSON

• Allow the express API to use the: Boolean, Array, and Number argument types
• Fallback to passing the raw string into express API
• Handles SyntaxException from JSON.parse

[rbkreisberg]

This allows us to send in a boolean value to the parameter for infrastructure like Heorku where we can't know the subnet address ahead of time.

@SamyPesse Let me know if you need anything else.

[SamyPesse]

I'm not a big fan of JSON parsing the env, but I don't see another solution in that case except, so LGTM.

[SamyPesse]

Thanks 👍