security/obfsproxy: Make argparse a conditional dependency

Backport a patch to setup.py making argparse a conditional dependency
to fix the following error at runtime:

pkg_resources.DistributionNotFound: The 'argparse' distribution was not found and is required by obfsproxy

While I'm here, pet portlint, USE_* comes before USES. Bump PORTREVISION.

PR: 223320
Submitted by: cpm
Reported by: Hadi <rezaee.hadi@gmail.com>
Approved by: cs (maintainer timeout, 2 weeks)