Add qpdf package

packages/qpdf.rb

+require 'package'
+
+class Qpdf < Package
+  description 'QPDF is a command-line program that does structural, content-preserving transformations on PDF files.'
+  homepage 'http://qpdf.sourceforge.net/'
+  version '7.0.b1'
+  source_url 'https://github.com/qpdf/qpdf/archive/release-qpdf-7.0.b1.tar.gz'
+  source_sha256 '2e0a26f7a03fe41c72be8e95c420744f98dbf553e025fb0d4c990f83df023d90'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  def self.build
+    system './autogen.sh'
+    system './configure'
+    system 'make'
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end