Merge pull request #432 from cstrouse/add-p7zip

Add p7zip (16.02) package

packages/p7zip.rb

+require 'package'
+
+class P7zip < Package
+  version '16.02'
+  source_url 'http://downloads.sourceforge.net/p7zip/p7zip_16.02_src_all.tar.bz2'
+  source_sha1 'e8819907132811aa1afe5ef296181d3a15cc8f22'
+
+  def self.build
+    system "cp", "makefile.linux_any_cpu", "makefile.machine"
+    system "make", "all3"
+  end
+
+  def self.install
+    system "make", "DEST_DIR=#{CREW_DEST_DIR}", "install" 
+  end
+end