Fix issue 410 and autosize not working for Reply box of non-html mail.

https://github.com/owncloud/mail/issues/410
and get to use jquery autosize in Reply box too for all mails, html and non-html
modifying a 3rdparty component is the wrong way to accomplish this.
I'd assume there is an options array to be passed into the autosize() call to change the defaults.

THX