New Root URL: Accept URLs in loose format similar to what regular browsers accept

[davidfstr]

Covers the following issues:

• [x] FTR-4.4: Initial text for URL field is "http://" which is a deprecated URL scheme. Should use "https://" instead, if anything.
• [x] FTR-4.5a: URL field permits entering obviously invalid URLs like "boom" without complaint. Only URLs with recognized schemes should be allowed.
• [x] FTR-4.5b: URL field doesn't clean/recognize the same kind of URL-like input that a regular web browser does in its URL bar.
  • For example "getmdl.io" should be rounded to "https://getmdl.io/".
  • "https://getmdl.io" should be rounded to "https://getmdl.io/" (with a trailing slash), and it currently appears to be. 👍