Auto merge of #86 - edunham:travis-fix, r=metajack
Auto merge of #86 - edunham:travis-fix, r=metajack

Install Salt from ppa rather than curl|sh

Old way was fragile, and broke, as noted most recently in https://github.com/servo/saltfs/pull/84#issuecomment-125971687 

It'd be even better to use Travis's containers, but that's blocked on https://github.com/travis-ci/apt-source-whitelist/issues/82 . Once Saltstack is an approved PPA, it'll be trivial to refactor the `.travis.yml` to stop using sudo as described in http://docs.travis-ci.com/user/migrating-from-legacy/ .

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rwaweber/saltfs,ALikhachev/saltfs,setupminimal/saltfs,rwaweber/saltfs,servo/saltfs,ALikhachev/saltfs,UK992/saltfs,UK992/saltfs,ALikhachev/saltfs,setupminimal/saltfs,rwaweber/saltfs,servo/saltfs,setupminimal/saltfs,UK992/saltfs