Add youtube-dl package (#2125)

packages/youtubedl.rb

+require 'package'
+
+class Youtubedl < Package
+  description 'Command-line program to download videos from YouTube.com and other video sites'
+  homepage 'http://rg3.github.io/youtube-dl/'
+  version '2018.03.20'
+  source_url 'https://github.com/rg3/youtube-dl/releases/download/2018.03.20/youtube-dl-2018.03.20.tar.gz'
+  source_sha256 'a977d04aa201ef35f8a6dc66b19204a9093b26c9d04d643089a1d467ba4e0682'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  depends_on 'python27'
+
+  def self.install
+    system "yes | pip install setuptools"
+    system "pip install --prefix #{CREW_PREFIX} --root #{CREW_DEST_DIR} -I youtube-dl==2018.03.20"
+    system "yes | pip uninstall setuptools"
+  end
+end