Print warning message when unescaped JS is detected

[carlosramireziii]

One of the most common errors in SJR templates is forgetting to escape your code for JavaScript.

To help alleviate this issue, we can try to detect unescaped render calls within any ERB tags and print a warning to the console.

• [ ] Add config item to toggle behavior
• [ ] Add documentation for this feature
• [ ] Add code documentation to new classes
• [ ] Bump gem version