updated the _set_database method to use a class variable for the database connection - this way, we don't override the global CI database variable
fixed typo
updating the tests to use _database instead of db
updating to load 'active_group' database if one is not defined
making _database public
Merge pull request #104 from swatkins/master

Use local database variable instead of CI `$this->db`
Fix DB connection issue; update docs.
Merge pull request #107 from cryode/bug/setdatabase

Fix DB connection issue, add supporting documentation.
Synchronizing with the original repository.