update changelog
only load autocompletion if it is available, see #101
Merge branch 'master' of https://github.com/travis-ci/travis
improve `travis logs`

* Have it display first job for a build if a build number is given (or for the last build if called without arguments)
* Add support for branch names.
* Add support for just using the job suffix.
* Improve error message if job cannot be found/identified.

Fixes #108.