Fixed bug [ticket:#16]: Configure mode to shutdown primary and standby
  database. Added DATABASE_SHUTDOWN and ASM_SHUTDOWN configuration variables
Checkpoint while work on ticket #14 and #17
 Fixed bug [ticket:#14]: Configure startup mode for database.
  Added DATABAS_STARTUP configuration variable

 Fixed wishlist [ticket:#17]: Add support for Dataguard Broker.
  New value 'DG' for DATABASE_ROLE variable.