Fix bug when count the number of problem solving

Some solvers can save the time spending solve the problem as 0.0
and this will break the scale due a division by zero. We solve
this problem using a regex to check if the time is zero and if it
was adding a epsilon.
Raise error if time spending is zero
Merge pull request #37 from r-gaia-cs/bug-counter

Fix bug when count the number of problem solving