Travis pass does not check existence of `polymer.json`

[TimvdLippe]

The Travis pass currently adds linting to the script (

tedium/cleanup-passes/travis.ts

Lines 78 to 83 in 3684899

	// Add polymer lint to all elements
	const beforeScript = ['polymer lint'];
	if (!Array.isArray(travis.before_script) ||
	!arraysEqual(travis.before_script, beforeScript)) {
	travis.before_script = beforeScript;
	}

), however this will fail if polymer.json does not exist in the repository (which is the case for almost all elements).

The Travis pass (or maybe a different pass) should therefore generate a simple polymer.json with the correct linting configuration. Probably for the elements this should be

{
  "lint": {
      "rules": ["polymer-2-hybrid"]
  }
}