Add support for travis CI

`python-zope.interface` was installed in aptitude, and it was an old version that doesn't have `registry`.  Removing it fixes the tests.

Skip cnxpublishing.tests in configurator scan
    
To fix the following error:
```
      File "/home/karen/cnx-publishing/cnxpublishing/main.py", line 31, in main
        config.scan()
      File "/usr/local/lib/python2.7/dist-packages/pyramid-1.4.4-py2.7.egg/pyramid/config/__init__.py", line 947, in scan
        ignore=ignore)
      File "/usr/local/lib/python2.7/dist-packages/venusian-1.0a8-py2.7.egg/venusian/__init__.py", line 199, in scan
        __import__(modname)
      File "/home/karen/cnx-publishing/cnxpublishing/tests/test_publish.py", line 16, in <module>
        import mock
    ImportError: No module named mock
```