Add coreutils package

packages/coreutils.rb

+require 'package'
+
+class Coreutils < Package
+  description 'The GNU Core Utilities are the basic file, shell and text manipulation utilities of the GNU operating system.'
+  homepage 'http://www.gnu.org/software/coreutils/coreutils.html'
+  version '8.27'
+  source_url 'http://ftp.gnu.org/gnu/coreutils/coreutils-8.27.tar.xz'
+  source_sha1 'ee054c8a4c0c924de49e4f03266733f27f986fbb'
+
+  def self.build
+    system './configure'
+    system 'make'
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end