add server.js, the main application file.
requiring modules
    - http for the server
    - fs for serving files
    - path to simplify relative requires
    - mime to derive a MIME type based on filename extensions
add cache objects to store contents of cached files
add a helper function to handle 404 errors
add a helper function that responds with the correct http headers and serves the contents of a file
add helper function that checks if a file is cached in memory and serves it if it isnt. Otherwise caches the file on its initial request and then serves it.
create a server listening on port 3000. Server sets up filepath and servers the static files
Merge pull request #1 from arcin/static_file_server

Static file server