fea: add Lua support for scripting

[marco-souza]

This PR adds Lua lang support adding customization.

I'm planning to use this for:

• cronjob scripting // task scheduler
• bots webhooks

Tasks

• create routes (/lua POST)
• create form to test on playground
• FIXME: get lua execution output (Support redirecting stdout/stdin/stderr to/from other sources Shopify/go-lua#43)

This closes #4

[marco-souza]

Actually, there is no need to implement the std redirect, as we can use os.Pipe to read form stdout and write using stdin.

Therefore, there is no need to wait for Shopify/go-lua#43

[marco-souza]

FYI, PR is created: Shopify/go-lua#135

[marco-souza]

go go go 🚀