Fixes from Tsuna's code review:
Changed Config class statics to public class fields, allows multiple TSDBs per app without the globals
Changed Config backing store to a HashMap instead of Properties as it's faster for access
Moved the os.name system property call to a one-time static in GraphHandler so it isn't making that call on every graph creation
Fixed some typos
Added Tsuna's checkNecessaryTablesExist() to TSDB to reduce the # of lines in each tool