Add waf package

packages/waf.rb

+require 'package'
+
+class Waf < Package
+  description 'The Waf build system'
+  homepage 'https://waf.io/'
+  version '1.9.12'
+  source_url 'https://github.com/waf-project/waf/archive/waf-1.9.12.tar.gz'
+  source_sha256 '1d33490f421560fd5ddb9dcc523c3c50e9dba0146ffac3e5f8503149cc10252c'
+
+  depends_on 'help2man'
+  depends_on 'python27' unless File.exists? '/usr/local/bin/python'
+
+  def self.build
+    system './waf-light configure build'
+  end
+
+  def self.install
+    system "mkdir -p #{CREW_DEST_DIR}/usr/local/bin"
+    system "mkdir -p #{CREW_DEST_DIR}/usr/local/man/man1"
+    system "help2man -N ./waf > waf.1"
+    system "cp waf #{CREW_DEST_DIR}/usr/local/bin"
+    system "cp waf.1 #{CREW_DEST_DIR}/usr/local/man/man1"
+  end
+end