Configuation format polishing

[mbarnes]

A bit of polishing around store handler configuration. Docs will be a separate PR.

Changes:

• Replace host/port/protocol keys with a single server_url. I think this is less cumbersome for users and I see other projects using URLs in their config files.
• A side-effect of the previous item is etcd.Client arguments are assembled from the config dictionary instead of config being passed through directly. I think this is safer.
• Wildcards in the models list makes accidental conflicts easier. Assigning a model to multiple store handlers now raises an error.

[rh-atomic-bot]

:umbrella: The latest upstream changes (presumably 1775790) made this pull request unmergeable. Please resolve the merge conflicts.

[mbarnes]

Rebased since merging the flanneld-server-client branch.

[ashcrow]

I recommend updating the addresses in the tests to non routable addresses or example.org. Otherwise looks good.

[mbarnes]

:arrow_up: Good call. Fixed.

[ashcrow]

LGTM

[ashcrow]

Let's see if homu+travis is happy this morning ....

@rh-atomic-bot r+

[rh-atomic-bot]

:pushpin: Commit aafc4b6 has been approved by ashcrow

[ashcrow]

@rh-atomic-bot try

[ashcrow]

I'll rebase and push manually.

[ashcrow]

Merged.