Consolidate Git status checking

Now the status bar and tree view both listen for
status change events and use the cached information
available from the git object to update their views.

src/app/git.coffee

@@ -38,6 +38,13 @@ class Git
         @refreshIndex()
         @refreshStatus()
 
+    project?.eachBuffer this, (buffer) =>
+      bufferStatusHandler = =>
+        path = buffer.getPath()
+        @getPathStatus(path) if path
+      @subscribe buffer, 'saved', bufferStatusHandler
+      @subscribe buffer, 'reloaded', bufferStatusHandler
+
   getRepo: ->
     unless @repo?
       throw new Error("Repository has been destroyed")

src/app/project.coffee

@@ -128,9 +128,15 @@ class Project
       buffers.push editSession.buffer
     buffers
 
-  eachBuffer: (callback) ->
+  eachBuffer: (args...) ->
+    subscriber = args.shift() if args.length > 1
+    callback = args.shift()
+
     callback(buffer) for buffer in @getBuffers()
-    @on 'buffer-created', (buffer) -> callback(buffer)
+    if subscriber
+      subscriber.subscribe this, 'buffer-created', (buffer) -> callback(buffer)
+    else
+      @on 'buffer-created', (buffer) -> callback(buffer)
 
   bufferForPath: (filePath) ->
     if filePath?

src/app/window.coffee

@@ -69,9 +69,11 @@ window.shutdown = ->
     rootView: rootView.serialize()
   rootView.deactivate()
   project.destroy()
+  git?.destroy()
   $(window).off('focus blur before')
   window.rootView = null
   window.project = null
+  window.git = null
 
 window.installAtomCommand = (commandPath) ->
   return if fs.exists(commandPath)