Bug 1095199 — Standardize callback and cb use.
Merge pull request #262 from mozilla-services/1095199-cb

Bug 1095199 — Standardize callback and cb use.
Refactoring — multiline error handling.

See http://stackoverflow.com/a/27038608/186202

Use: grin 'if \(err\)' loop/ test --emacs | egrep -v 'throw' | egrep -v 'return'
To verify.