show build status of current branch

And lots of other error handling so you don't have to open the console.
`4. The package will keep trying to get build status unless it was unable to log in.`

Yes; the reason is a side-effect due to the support for branches. Previously you were getting the most recent builds regardless of which branch you were on -- if it failed, the project wasn't registered with Circle (a valid reason to stop polling). Now, until you push a branch, there will be no build status; I don't (have to) do any verification that the project exists -- I just make the full API call to Circle and it either succeeds or it fails (the project and branch pair are just part of that).

Otherwise you would have to close and reopen Atom every time you switch a branch or push it, if it wasn't already in circle and being tracked, even if the project IS being tracked.

FWIW I've never been anywhere near Circle's authenticated API limit using this plugin. And I keep in close contact with their team.