This helper allows nicely formatted JSON to be sent the the client as
single-line JSON text.

rules:
- path: "/static/minify"
  methods: ["GET"]

  responses:
  - status_code: 200
    body: |-
      {{ minify_json `
      {
      	"key1": "value1",
      	"key2": "value2"
      }
      `}}

will respond to requests to /static/minify with {"key1":"value1","key2":"value2"}.