Pass credentials to allow git pull in tasks

[venth]

Hi,

currently we try to rebase a commit fetched by gerrit resource against master. The commit rebase is done in a separate task. Unfortunately credentials and git metadata aren't passed along the sources which made git pulling to end with an error.

The change is about passing git metadata and credentials along the sources.

[lann]

I'm not sure I understand exactly what you are trying to do, but I think you would be better served by sharing these parameters in your concourse config file. You can even deduplicate using YAML anchors/expansion (i.e. http://blog.daemonl.com/2016/02/yaml.html).