* Buildfix: explicitly upgrade setuptools

With 2.7 required, both builds for 3.x and 2.x failed with following error
"
VersionConflict
(setuptools 12.0.5
  (/home/travis/virtualenv/python3.4.2/lib/python3.4/site-packages),
  Requirement.parse('setuptools>=30'))
"

* Exit with non-zero code on single run error

If flag --once is specified, and some error occurs exit with
code 1.
Additional test for main function.