Adding the installation of libffi-dev. Fixes #239.
Some travis and ansible fixes.
Fixing CherryPy version to 3.3.0
Set parallel level back to 4.
Removing debugging output.
Merge pull request #241 from girder/libff-doc-fix

Adding the installation of libffi-dev. Fixes #239.
Merge remote-tracking branch 'origin/master' into admin_user_checkbox

* origin/master:
  Removing debugging output.
  Set parallel level back to 4.
  Fixing CherryPy version to 3.3.0
  Some travis and ansible fixes.
  Adding the installation of libffi-dev. Fixes #239.