Add a global pasteboard object which supports metadata

This metadata will be used to record the indentation level of the first line when copying multiple lines of text to the pasteboard. The pasteboard takes the md5 of the pasted content when writing, then when reading it associates the last written metadata only when the signature matches the previously written value.

src/app/window.coffee

@@ -9,6 +9,7 @@ _ = require 'underscore'
 $ = require 'jquery'
 {CoffeeScript} = require 'coffee-script'
 RootView = require 'root-view'
+Pasteboard = require 'pasteboard'
 require 'jquery-extensions'
 require 'underscore-extensions'
 
@@ -24,6 +25,7 @@ windowAdditions =
     TextMateBundle.loadAll()
     TextMateTheme.loadAll()
     @setUpKeymap()
+    @pasteboard = new Pasteboard
     $(window).on 'core:close', => @close()
 
   # This method is intended only to be run when starting a normal application