Updated Readme and Rakefile for local gameplay

Rakefile
Rakefile was updated to have a play option that opens localhost port 8000 which is the port that python opens up a server

Readme
Added directions to play game locally
Added explaination for using the latest devlopment release of CasperJS
Added a list of the files to update if using a server other than python SimpleHTTPServer
Merge pull request #15 from zachmokahn/11-updating_readme

Updated Readme and Rakefile for local gameplay