[Checkins] [zopefoundation/ZEO] bc92bd: Add caching

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/ZEO
  Commit: bc92bdd7e8e384eab0a256a9ab049f23eea62431
      https://github.com/zopefoundation/ZEO/commit/bc92bdd7e8e384eab0a256a9ab049f23eea62431
  Author: Jim Fulton <jim at zope.com>
  Date:   2016-08-05 (Fri, 05 Aug 2016)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  Add caching

Mainly to have a backup cache for new branches (although this won't
help that much because of the differences between ZEO4 and ZEO5,
still...

Also stop testing on mac. I do that enough already. :)

Also, use a simpler leaner install script.