Task 6: Added King Arthur to Codalot. Added the Round Table destination. Added logic to not award XP to knights that don’t visit the round table the minimum amount of times

- Knight.java
  - Added setIsKingArthur and isKingArthur methods
  - Added isInRoundTable, incTimesAtTheRoundTable and timesAtTheRoundTable methods

- Codalot.java
  - Added addKnightToRoundTable method
  - Added the throw of a run time error if the required fields are not passed in within the config

- Main.java
  - Added king arthur to codalot
  - Displaying king arthur’s stats separate from the other knights
  - Added the Round table destination when randomly selecting a place to put a knight
  - Added call to check whether each knight visited the round table the minimum number of times
  - Added some error handling to verify that the required config values are in the config file

- KnightTest.java
  - Added unit test for isKingArthur and setIsKingArthur methods
  - Added unit tests for isInRoundTable, incTimesAtTheRoundTable and timesAtTheRoundTable

- CodalotTest.java
  - Added unit test  for addKnightToRoundTable
  - Added unit test for checkVisitsToRoundTable

- codalot_config.json
  - Added ROUND_TABLE_MIN_VISITS config value