replaced elnode with emacs-web-server

  This works around some issues I was having with elnode.  Namely, it
  seemed slow, overly complicated, unreliable and generated huge amounts
  of information-less logs.

  Emacs web server [1] is simpler and does seem to be faster in my
  experience so far.

  [1]  https://github.com/eschulte/emacs-web-server
updated for changes to ews
use new ews in-directory checking function
rename Emacs Web Server prefix ews -> ws
emacs-web-server to web-server
fix compilation errors
add commentary
switching from marmalade to melpa