Prevent exception when no coincidences are found

ProgressBar does not work for empty iterables.
Prevent progressbar update on a comment line

Fixes #14
Add travis.yml for Travis CI tests
Ensure libhdf5 and numexpr are installed

Previous build failed because PyTables required numexpr, so install it
first
Code from: https://github.com/PyTables/PyTables/blob/master/.travis.yml
Also install Cython for PyTables
Install requirements for scipy
Another attempt to get setup working on Travis

SciPy/NumPy require special care.
Install numexpr and Cython after conda stuff
Merge branch 'master' into refactor_simulations

This merge is meant to get the Travis CI config into this branch