Revision on Rock-Paper-Scissors-Lizard-Spock game

The following changes are made for my second version of RPSLS:
-Fixed the problem if user input is out of the five words: give an
invalid warning.
-Added a loop so the game can continue.
-Added counter to keep track of number of tries, users win/tie against
the computer.
-Give user exit point when each new round starts.
-Count down the number of rounds played (5 times) and give summary at
the end of the game or when exit voluntarily.