Share a project with any group

Zendesk: https://gitlab.zendesk.com/agent/tickets/13625
GitLab version: 8.2.3
Customer requests that an admin can have access to view all groups to chose which to share a project with. Instead of the current behaviour of only viewing groups he/she has access to.

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Edit:

GitLab version:
This issue has been changed to a bug because this functionality was already available previously.

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What do you think about this one @JobV?

cc/ @vsizov