Clone full repo history in Travis
Clone full repo history in Travis

Rather than doing a shallow clone, always clone the full Git repo. This
helps with:

- setuptools_scm, so it can count commits in very long branches (longer
  than 50 commits)

- The documenteer.sphinxconfig.utils tools for inspecting Git history
  need the repo's full history for their tests.

lsst-sqre/documenteer,lsst-sqre/documenteer,lsst-sqre/sphinxkit