Use ID instead of Id (go style) everywhere

Fixes #278
Merge pull request #321 from smarterclayton/use_capital_id

Use ID instead of Id (go style) everywhere
travis: add go 1.3 target
travis: temporary disable tip

workaround gofmt failure, until #322 is in
Merge pull request #323 from proppy/master

travis: add go 1.3 target
Change error printing for easier debugging
Fix interface{} in api/types.go; plumb through system.