examples: Get web-file-browser.php to work with an existing web server setup.

Should now work with an Apache/mod_php-style web server setup, as well
as with "php -S".
Move "test/strict.php" "lib/Dropbox/strict.php" so others can use it.

Was using it in example code.  Decided it was bad for the examples to
have a dependency on the "test" folder.