2.2.1 release
Silence deprecation warning for /usr/bin/atos.

`callSiteWithAddress` uses the `atos` command line tool
tool, which outputs the following to stderr when run on OS X 10.9
(13A569) & XCode 5 GM:

```
--
Warning: /usr/bin/atos is moving and will be removed from a future OS X release.
It is now available in the Xcode developer tools to be invoked via: `xcrun atos`
To silence this warning, pass the '-d' command-line flag to this tool.
--
```

This commit silences the warnings.
Remove failing brew command from travis.yml.
Don't use libunwind on ARM.
xctool needs SDK specified.
Merge pull request #367 from modocache/fix-travis-yml

Fix Travis CI tests.
Merge pull request #365 from modocache/silence-atos-warning

[v2.2.1] Silence deprecation warning for /usr/bin/atos.
Merge remote-tracking branch 'upstream/master' into classes-in-failure-message