Simple template for JSON output

[jaromil]

As a feature it should be possible to structure the JSON output by loading a template and filling it with values. It is simple to implement using Lua's string class, these modules may be of some inspiration:

• https://github.com/bungle/lua-resty-template
• https://github.com/Olivine-Labs/lustache

[jaromil]

This is even more feasible using the context input channel (free form) to attach all outputs to a template of any kind.