Footer: Consolidate contributor links

[medubelko]

Based on a discussion of the GitHub links in the footer, @evildmp and I think it would be a good idea to limit the number of calls to action for contributors in the footer.

We should:

1. Rethink the design and pare down the links as much as possible, optimally one or two, to make the presentation look less fussy.
2. Constrain the customisation of the footer in the template itself.

@SecondSkoll let me know if you'd rather I spin this off as a Jira task.

[SecondSkoll]

So, this doesn't come under the umbrella of "starter pack simplification" in my mind, but I do support the change. I'll create a separate non-roadmap epic on Monday for items like this.

Bear in mind that this would be considered lower priority than roadmap items, though it's possible @evildmp would consider this to be part of the simplification epic.

[medubelko]

Not a problem. This would be mine to take on, effectively.