Since packstack introduced a DB_PW for each module, it started failing
when 1 of those modules is not marked for install because of some
missing variables in the CONF dict when formatting mysql.pp
This patch splits mysql configs per module in 3 different pp files and
includes them just when those modules are marked for install.
Fixes bz#903191
Change-Id: I7c1d86c7c80aa6e801f0ea68e2379abc01ab4967