Fix travis

[jchodera]

Looks like something changed upstream with mock:

======================================================================
ERROR: Failure: ImportError (No module named funcsigs)
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Traceback (most recent call last):
  File "/home/travis/miniconda/envs/test/lib/python2.7/site-packages/nose/loader.py", line 418, in loadTestsFromName
    addr.filename, addr.module)
  File "/home/travis/miniconda/envs/test/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
    return self.importFromDir(dir_path, fqname)
  File "/home/travis/miniconda/envs/test/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
    mod = load_module(part_fqname, fh, filename, desc)
  File "/home/travis/miniconda/envs/test/lib/python2.7/site-packages/ensembler/tests/test_gather_templates.py", line 9, in <module>
    from mock import Mock
  File "/home/travis/miniconda/envs/test/lib/python2.7/site-packages/mock/__init__.py", line 2, in <module>
    import mock.mock as _mock
  File "/home/travis/miniconda/envs/test/lib/python2.7/site-packages/mock/mock.py", line 80, in <module>
    import funcsigs

I'm not sure why this is suddenly happening, since mock and funcsigs packages on anaconda haven't changed recently.