Added nomodeline to vim command

Responding to a message using the CLI calls `vim` to edit an untrusted text (the received message with '>'). This might be exploited by a message sender that includes a malicious modeline into the text of the message.

> there is always a small risk that a modeline
> causes trouble.  E.g., when some joker sets 'textwidth' to 5 all your lines
> are wrapped unexpectedly.  So disable modelines before editing untrusted text.
> The mail ftplugin does this, for example.

[Source : the official vim documentation](http://vimdoc.sourceforge.net/htmldoc/options.html).

That's why I would be better to disable modeline interpretation.