R1:9b56c7e8a125

Create script printing controller name based on URL

Summary:
With this script, I am able to add bookmarklet to my browser which edits the
controller responsible for displaying current page by a single click.
Plus it can be useful also for other uses.

Test Plan:
./aphrontpath.php /
./aphrontpath.php D123
./aphrontpath.php /D123
./aphrontpath.php /D123/ # doesn't exist
./aphrontpath.php https://secure.phabricator.com/D123
./aphrontpath.php https://secure.phabricator.com/D123?x=2
./aphrontpath.