Add package for pv (1.6.0)

This adds pv (pipe viewer) version 1.6.0. The pv command allows you to monitor the progress of data as is passes through command pipelines.

Tested as working properly on Samsung XE50013-K01US. All tests pass when running `make test`.

packages/pv.rb

+require 'package'
+
+class Pv < Package
+  version '1.6.0'
+  source_url 'http://www.ivarch.com/programs/sources/pv-1.6.0.tar.gz'
+  source_sha1 '395ce62f4f3e035b86c77038f04b96c5aa233595'
+
+  def self.build
+    system "./configure"
+    system "make"
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end