* Simplify browserless script and catch errors

* Improve fetching body:
    - follow up on max. 4 redirects
    - rely on Req default timeouts (wait much longer to account for slow
      sites)

* Improve installation check:
  - rely on Req default timeouts, wait longer
  - log service errors as warnings
  - use stealth mode to bypass captchas

* Stop cutting off body too large

* Improve diagnostics for known failures

* Another round of diagnostic improvements

* Format

* Add a test for callback status 500