[FIX]Fixed the issue of reference field throws traceback that view is...

[FIX]Fixed the issue of reference field throws traceback that view is undefined, the reason is that reference field passing DefaultFieldManager while creating instance of many2one widget and DefaultFieldManager is eventually extending instance.web.widget not instance.web.form.FormWidget and hence DefaultFieldmanager will nto having view attribute, instead of calling self.view.do_onchange, trigger changed_value which is going to do the same job.

bzr revid: msh@tinyerp.com-20140416083857-sug0k4a28nkvgg27