Add test for timing values on second running
Restart @elapsed, @start and @finish instance variables

The current algorithm relies on the fact that these instance
variables are set to nil upon start.

But, their last values are saved on the instance and this fact
causes the issue #4 when running the cursor for the second time
on the same script.
Merge pull request #5 from abinoam/master

Add test and restart instance variables values