Changed remaining subclasses of Stat to inherit from Record.

- Changed HouseStat and TourneyStat classes to inherit from Record
- Ported exists() method into Record from Stat
- Deleted Stats.java
- Updated code to reflect usage changes from Stat to Record
Modified getTotalPlayers() method for DB (issue #125).

- Updated the getTotalPlayers() method for all games to query from
  stats.sqlite3 instead of players.txt
Modification of get() in Player classes.

- Modified get() in Player classes to return the proper values for given
  keys
- Updated getPlayerStat() in CardGame classes to return Object instead of
  int
Removed loadPlayerData() and savePlayerData() (issue #125).

- Games now solely rely on stats.sqlite3 for player data storage for
  loading and saving data
- Removed prefixes for "winnings" and "rounds" keys for TexasPoker and
  Blackjack as they are no longer required
- Renamed TexasTourney stats "ttplayed" and "ttwins" to "tourneys" and
  "points"
- Updated loadDBPlayerData() to ensure stats keys are initialized
- Migration from players.txt to stats.sqlite3 can now only be done
  automatically through the "migrate" command
Implemented loadDBPlayerRecord() to replace old methods. (issue #125)

- Updated "migrate" command and strlib.txt with a no_migrate message
- Removed loadPlayerRecord(), getPlayerStat(), checkPlayerFile() methods
  from CardGame
- Implemented loadDBPlayerRecord() as a replacement for loadPlayerRecord()
  and getPlayerStat()
- Updated showPlayerStat methods in all games to make use of
  loadDBPlayerRecord()
- Replaced a few get() calls with getInteger() for Records