Fix Filesystem::executeRemovePath

Summary:
Filesystem::remove() (implemented by executeRemovePath()) was broken for
symlinks to directories because is_dir returns true for symlinks to directories
in php.

Test Plan:
Tested in hphpd that is_dir() returns true for symlinks to directories, and that
unlink() instead of rmdir() will remove them (rmdir() won't remove them).
I haven't tested this code specifically.

Reviewers: epriestley, vrana

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4861
Disable cURL protocols other than HTTP and HTTPS

Summary:
See here for lols:

http://blog.volema.com/curl-rce.html

Although I'm not terribly worried about someone actually building a payload for this and mounting an attack, the underlying behavior is very silly. Shut this class of things down so that we never have to debug `arc` raising FTP errors, if nothing else.

Test Plan: Ran `arc` network commands.

Reviewers: btrahan, vrana, indiefan

Reviewed By: indiefan

CC: indiefan, aran

Differential Revision: https://secure.phabricator.com/D4864