Add missing packages to tempest element

Attempts to use this element failed due to missing the
following packages:
libssl-dev libffi-dev

This patch adds the packages to the element, including
pkg-map installs and map files.

Also changing shell called in init.d/51-tempest to be /bin/bash.

Change-Id: I6859e4309cc73127ac389de70c829ac59afcfd91
Closes-Bug: #1379047
Merge "Add missing packages to tempest element"