Switch to scalac 2.11.2.

This also required updating a couple third-party packages, which
required updating our code to their new API (minor).

And the new compiler has already found two bugs, also fixed here.
Merge remote-tracking branch 'upstream/master' into ready/scalac-2.11

Need updated integration tests.
A few improvements to the `ready` script.

* fetch _all_ remotes (was missing upstream, which meant we didn’t merge
  all changes)
* fix origin branch check
* Switch to safer bash constructs – `$()` instead of backticks and
  `[[]]` instead of `[]`
Merge pull request #291 from sellout/ready/git-workflow-changes

A few improvements to the `ready` script.
Merge pull request #290 from sellout/ready/scalac-2.11

Switch to scalac 2.11.2.