Use bash to suppress schema load output

On Ubuntu, suppress_output doesn't work because Ubuntu uses dash for
/bin/sh [1] which doesn't support pipefail.  This uses /bin/bash
instead.

[1] https://wiki.ubuntu.com/DashAsBinSh
Fix specs to work with new suppress_output
Merge pull request #283 from blt04/suppress-output-bash

Fix suppress_output on Ubuntu