Namespace license checks for contribution analytics

Related to https://gitlab.com/gitlab-org/gitlab-ee/issues/2335

Contribution analytics (EES / Bronze)

1. Do not show Analytics tab under group menu

2. Return 404 for /groups/<groupname>/analytics

3. Question: Could we return the little-used 402 status code and potentially create a payment required page that shows the plans with a link to buy?

Expert: @dzaporozhets

mentioned in issue #2335 (closed)

assigned to @to1ne

mentioned in merge request !2279 (merged)

mentioned in merge request !2302 (merged)

mentioned in commit 6217bd23

closed via merge request !2302 (merged)

mentioned in commit cd94370f