Contact Form: do not display the logged in user's details

Can be overwritten with the jetpack_auto_fill_logged_in_user filter
Fixes #694l
Contact Form: fix spacing

See https://github.com/Automattic/jetpack/pull/725#commitcomment-6888035
Merge pull request #726 from jeherve/grunion_noemail

Contact Form: do not display the logged in user's details