Add unit test

Added unit test on perimeter functions
Fix calculation and sys args bugs

Fixed calculation of a polygon perimeter.

- main function renamed to calculate length for unite testing.
- if there is only one point the distance array is empty, if 2 point
there is only one line, for more than 2 there are N lines for M points
- added feature in sys args to load all the csv files
Rename buggy_perimeter to csv_perimeter_calculator