Repos Should be Able to be Grouped

[isugimpy]

Today, when you acquire you do so for a whole channel. This leads to a scenario where we have a lot of salons and it becomes challenging to manage. As a proposed alternative, register repos to a channel, and also optionally register repos to a meta-repo group within that channel, with the intent that the groups would comprise components that are explicitly linked in a meaningful way such that they should block each other. Then, when a person acquires, require them to specify a repo, group, or the whole salon as what they're acquiring. If you acquire a repo, and it's in a group, automatically bubble up to acquire the whole group. If you acquire a whole salon, block the acquire queue for the whole salon, similar to a hold. This would help increase visibility and decrease channel list volume, and put us in a better situation where we don't have (for example) puppet acquires blocking deploys of VCL, as they're unrelated.