BUG: numpy changed behavior for all-nan arrays.
Python 2.6 with `system_site_packages: true` was broken.
Merge branch 'fix/travis-ci' into fix/all-nans
Merge pull request #196 from enthought/fix/all-nans

BUG: numpy changed behavior for all-nan arrays.
Merge remote-tracking branch 'upstream/master'
in order to get Travis CI to work