Present repos with > 1 Go package in a better way.

Output is valid import path pattern for go get, go list.
Output is deterministic (except order). Fixes #13.
Remove command/library distinction "/", as that isn't relevant on a
per-repo level.
Display "!" instead of "+" for repos with no remote (hence remote
revision cannot match local revision). Fixes #12.
Remove solved caveat from README.
Update Godeps.
Update sample output to be representative of current format.

Also change language to highlight that the root folder of repository is
the displayed unit, rather than a random Go package inside the repo.
This is indicated by the trailing "/..." pattern.
Merge pull request #15 from shurcooL/next-iteration

Present repos with more than 1 Go package in a better way.