This will ensure that the database connection given is ready for use. If it does not find the tables it needs, it will try to create them.
This can be either a filename, in which case we assume it is the name of an SQLite database and use RSQLite to connect to it, or else any DBI Connection.
Returns a connection object that can be used with other database oriented functions.
#create and initialize a new SQLite database conn = initDb("test.db")