Added skeleton for insertion_sort. Implemented tests for insertion sort.
Implemented insertion sort. Test is passing.
Reduced number of insertion sort tests from 1000 to 100 (they take a long time).
Added newline to end of test_insertion_sort.py.
Added demonstration code to if __name__ == '__main__' block in insertion_sort.py.
Added tests for insertion sort to Travis file.
Updated readme with information on insertion_sort.