Adopt official DB2 Express-C docker image

[sirnewton01]

At the moment, the automation assumes that the user will provide a DB2 express c tar ball and uses that to assemble an image. Instead, it should use the official DB2 image hosted on docker hub.

[sirnewton01]

https://hub.docker.com/r/ibmcom/db2express-c/

[mbarqawi]

you mean that it will not work without providing the DB 2?