Restore window when opening path

Previously the window would stay minimized if it was triggered
from the command line and was already open.

Closes #1889

src/browser/atom-application.coffee

@@ -311,6 +311,7 @@ class AtomApplication
     if existingWindow
       openedWindow = existingWindow
       openedWindow.openPath(pathToOpen, initialLine)
+      openedWindow.restore()
     else
       if devMode
         try

src/browser/atom-window.coffee

@@ -151,6 +151,8 @@ class AtomWindow
 
   maximize: -> @browserWindow.maximize()
 
+  restore: -> @browserWindow.restore()
+
   handlesAtomCommands: ->
     not @isSpecWindow() and @isWebViewFocused()