add python27 package

packages/python27.rb

+require 'package'
+
+class Python27 < Package
+  version '2.7.8'
+  source_url 'https://www.python.org/ftp/python/2.7.8/Python-2.7.8.tgz'     # software source tarball url
+  source_sha1 '511960dd78451a06c9df76509635aeec05b2051a'          	# source tarball sha1 sum
+  
+  def self.build                                                  # self.build contains commands needed to build the software from source
+    system "./configure"
+    system "make"                                                 # ordered chronologically
+  end
+  
+  def self.install                                                # self.install contains commands needed to install the software on the target system
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"          # remember to include DESTDIR set to CREW_DEST_DIR - needed to keep track of changes made to system
+  end         
+end