Added support for MQ 7.5

[gpborges]

Added a new Dockerfile which adds support to MQ 7.5. I built it using command:

$ docker build -t mq:7.5 -f Dockerfile-mq7.5 .

I tested this in a RHEL 7.3 machine (IBM Open Client) running kernel 3.10.0-514.10.2.el7.x86_64

I ran it using:

docker run --name mq -e LICENSE=accept -e MQ_QMGR_NAME=QM1 -v $HOME/mqm:/mnt/mqm -p 1414:1414 -p 9445:9443 -d --ipc=host mq:7.5

And then, to validate it I used:

$ docker exec -it mq dspmqver
Name:        WebSphere MQ
Version:     7.5.0.2
Level:       p750-002-131001_DE
BuildType:   IKAP - (Production)
Platform:    WebSphere MQ for Linux (x86-64 platform)
Mode:        64-bit
O/S:         Linux 3.10.0-514.10.2.el7.x86_64
InstName:    Installation1
InstDesc:    
Primary:     Yes
InstPath:    /opt/mqm
DataPath:    /var/mqm
MaxCmdLevel: 750
LicenseType: Developer

[parrobe]

Hi Gabriel,

Thank you for the PR, I've got a couple of issues and points to bring up with you:

1. The master branch of this repository contains the latest Docker image and a single docker file (901). Whilst we used to have multiple docker files for multiple versions of MQ we moved these different versions of MQ into separate branches in Pull Request V2 changes #46. If we were to create a 7.5 version of the docker image then it would need to be in a separate branch (see the mq-8 & mq-8-lts streams as an example).
2. The scripts here have been created and tested to work with IBM MQ version 8 and above. I'm unsure whether they would be backward compatible. Have you performed any testing to make sure they all still work?
3. It's unlikely that we'd want to support a 7.5 version of the docker image as 7.5 is due to go out of service in April 2018. I'll discuss with colleagues here and get back to you.
4. In order to have your changes accepted you'll need to agree to the IBM Contributor License Agreement. See Issues and contributions for more information.

I'll be rejecting this PR based on the reason outlined in point 1. However i would suggest you don't start moving forward with a new PR until i or @arthurbarr gets back to you regarding point 3

[parrobe]

See my other comment

[parrobe]

We've discussed 7.5. The announcement for MQ Support in Docker containers was for MQ 8 and above. 7.5 is not covered in this and so is not supported by IBM to run in Docker containers. As this Github repository shows examples of MQ in docker containers we can't accept this PR.