[FAB-5434] Fix mysql config in fvt image
[FAB-5434] Fix mysql config in fvt image

Ubuntu 16.04.1 recently updated the default
mysql-server package to version 5.7.19.
This is causing fvt tests in CI to fail
on x86_64 (s390x uses Debian Jessie which
uses mysql 5.5.55 so is not affected).

This change is based on work in the
mysql images available on Dockerhub.
The change basically dismisses the
postInstall config and initializes
the database and sets the password
when the image starts up.

Change-Id: Ia8cb6a7faa77a5712a8ebf4d061215186c491e5e
Signed-off-by: Gari Singh <10008a422f4be611b73174084ba2f7f909d5b402@gmail.com>

saadk10/fabric-ca,saadk10/fabric-ca