Add Files View Refresh Support

[pq]

[user request]:

Add something to refresh project (now you need to close and reopen the editor).

[pq]

A context menu was added here: https://chromiumcodereview.appspot.com/9703036/

Follow on menu item and keybinding affordance requests are being tracked here: http://code.google.com/p/dart/issues/detail?id=2173

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Added Fixed label.