Feature/configure prometheus to scrape metrics from spark job pods/#23

[oliver-tarrant-tessella]

Including the processes to build a spark image containing necessary components to get spark metrics. This also incorporates #71. At present the spark operator is still not correctly built to expose the metrics on the pod. Hopefully in the future this will change. This pull request incorporates the latest version of the spark operator but also the wiki has been updated with instructions on how to update the operator if and hopefully when the spark operator is fixed (https://github.com/ukaea/piezo/wiki/BuildingASparkDockerImage)

[robert-clegg-tessella]

Looks great, only spotted a broken link in the Wiki page:

## The docker file

The docker file for the spark image can be found in the folder [Spark]().