Changed to accept '/' URL and simplified the options list

- Changed to accept the '/' URL since some load balancers use that.

- Changed the Allow header to add the HEAD method and remove POST,
  PUT, DELETE methods, since they are generally unused on the main
  page.

  (The application can customise this as needed.)
Updated Changes accordingly

Reformatted Changes in accordance with the
[CPAN::Changes::Spec](https://metacpan.org/pod/CPAN::Changes::Spec).
Added tests
Merge pull request #1 from robrwo/tweaks

Added / for alternative load balancers