don't decode file argument as unicode; tell user to file>import if broken

When the file to import has non-latin characters in its path, we're not
handling the provided filename correctly. I tried decoding with
sys.getfilesystemencoding() with no luck, so this needs more looking into. In
the mean time, if we can't open the path name, tell the user to File>Import
the file instead.

aqt/__init__.py

@@ -128,7 +128,6 @@ class AnkiApp(QApplication):
             self._srv = QLocalServer(self)
             self.connect(self._srv, SIGNAL("newConnection()"), self.onRecv)
             self._srv.listen(self.KEY)
-            # if we were given a file on startup, send import it
         else:
             # we accept only one command line argument. if it's missing, send
             # a blank screen to just raise the existing window
@@ -155,7 +154,7 @@ class AnkiApp(QApplication):
             sys.stderr.write(sock.errorString())
             return
         buf = sock.readAll()
-        self.emit(SIGNAL("appMsg"), unicode(buf))
+        self.emit(SIGNAL("appMsg"), buf)
         sock.disconnectFromServer()
 
     # OS X file/url handler

aqt/main.py

@@ -1055,6 +1055,6 @@ Please ensure a profile is open and Anki is not busy, then try again."""),
             return
         # import
         if not os.path.exists(buf):
-            return showInfo(_("Provided file does not exist."))
+            return showInfo(_("Please use File>Import to import this file."))
         import aqt.importing
         aqt.importing.importFile(self, buf)