Just set a boolean to indicate Neumann BC sign
Just set a boolean to indicate Neumann BC sign

It was stupid to have the user pass a number since this will always
be either 1.0 or -1.0. So just use a boolean to indicate which one
we want.

nicholasmalaya/grins,nicholasmalaya/grins,nicholasmalaya/grins,nicholasmalaya/grins