More development ease

The vagrant user can sudo with no password, so run the Meteor installer
not as root so we don't download all of Meteor twice.

I don't know if Meteor still downloads twice the old way, but it used
to.
Redo mobile assignment layout - fix #9, fix #13

Since #13 was because the checkbox was also a link, and I forced the
checkbox to quit being a link, #13 gets fixed here too!