Insert a node at tail of a linked list

More practice on May 9, 2016
Linked List on HackerRank:
problem statements:
https://www.hackerrank.com/domains/data-structures/linked-lists/difficulty/all/page/1


Insert a node at tail of a linked list
https://gist.github.com/jianminchen/957d2025fd310a9e59fb88fe8766e0de