Added Universal Database Option

User can now pick sqlite, postgres or mysql to use as their database.
All that needs to be changed is the yml file.  Removed unnecessary self
calls in the database file.  Added cli options in smbexec.rb.  Changed
cli prompt from sqlite to shell.
Multiple DB support

Fully tested with SQLite and Postgres.  The user can choose what db they
would like to use in the yml file.  If the driver is sqlite, the rest of
the information can stay blank.  If the driver is postgres, the user,
pass, host, port and db need to be filled out.  No other code needs to
be changed, importing into the db works, and pulling information out of
the db also works without trouble.
Merge pull request #92 from b00stfr3ak/add_database

Add database, updates gemfile with pg, updates yml config, updates sql shell