Fix Lint.jl warnings and errors
Add Verlet integrator
Small corrections about units and Float64 consistency
Change responsablity of Integrator

They now have to call the get_forces method when they need it.
Add EnergyCompute

This compute and store potential, kinetic and total energy
Update .travis.yml with new testing framework
Add code coverage tests
Also set the UnitCell whit the set_cell method
Fix the UnitCell constructors
Add == operator for UnitCell
Add tests for the Distances module
Fix the Distances module tests
Fix the distances computations for Orthorombic boxes

This is the end of a 3 week long bug seeking \o/
Fix the forces and energy computations
Test for Energy conservation in simulations
Fix RDF computation.

Why does this only fails now ?
Merge branch 'master' into UE210