Update to go1.1.

This commit updates the documentation, Makefiles, formatting, and
code semantics to support the 1.1. runtime, which includes ...

1. ``make advice``,

2. ``make format``, and

3. ``go fix`` on various targets.
Include "Travis Helper".
Merge pull request #245 from prometheus/feature/runtime/go1.1

¡ DONOTMERGE — Update to go1.1. !