test function is not working outside PBxplore folder

[HubLot]

Hi,

By playing with conda to create a conda package, I realized that the test function I implemented in #122 doesn't work outside the PBxplore folder package :

(pbxplore)[santuz@temple:~]$ python -c 'import pbxplore; pbxplore.test()'
/home/temple/santuz/projets/depots/PBxplore/pbxplore/tests
PBxplore version 1.3.1
numpy version 1.11.0
numpy is installed in /home/temple/santuz/.virtualenvs/pbxplore/local/lib/python2.7/site-packages/numpy
MDAnalysis version 0.14.0
MDAnalysis is installed in /home/temple/santuz/.virtualenvs/pbxplore/local/lib/python2.7/site-packages/MDAnalysis
matplotlib version 1.5.1
matplotlib is installed in /home/temple/santuz/.virtualenvs/pbxplore/local/lib/python2.7/site-packages/matplotlib
weblogolib version 3.4
weblogolib is installed in /home/temple/santuz/.virtualenvs/pbxplore/local/lib/python2.7/site-packages/weblogolib
Python version 2.7.6 (default, Mar 22 2014, 22:59:56) [GCC 4.8.2]
nose version 1.3.7

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Ran 0 tests in 0.102s

OK

I found the bug and I'll create a PR

[HubLot]

fixed in #130