add package for bash completion

packages/bash_completion.rb

+require 'package'
+
+class Bash_completion < Package
+  description 'Programmable completion functions for bash'
+  homepage 'https://github.com/scop/bash-completion'
+  version '2.7'
+  source_url 'https://github.com/scop/bash-completion/archive/2.7.tar.gz'
+  source_sha256 'dba2b88c363178622b61258f35d82df64dc8d279359f599e3b93eac0375a416c'
+
+  depends_on 'autoconf'
+  depends_on 'automake'
+
+  def self.build
+    system "autoreconf -i"
+    system "./configure"
+    system "make"
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+    puts "Add the floowing to your .bashrc"
+    puts "[[ $PS1 && -f /usr/local/share/bash-completion/bash_completion ]] && \"
+    puts ". /usr/local/share/bash-completion/bash_completion"
+  end
+
+end