Move most undercloud params to an environment file

This is my effort to replicate new changes from overcloud
I26f91980971fd4598b043bdb764359ac32a3c42a to undercloud as well.
Heat environment files give us a way to serialise the parameters
needed to create a stack easily.

Change-Id: I8ff50ca092e1209167cd9818b680f56a7512bba3