MAINT disable verbose tests on travis
MAINT Move the build_ext --inplace call to install.sh

In the travis UI, the output of the build step (from
continuous_integration/install.sh) is folded away when the that step
suceed making it easier to focus on the actual test outcome.
Merge pull request #3441 from ogrisel/travis-no-verbose-tests

MAINT disable verbose tests on travis