Correctly parse set_table_name string with owner

Currently, if the table name string passed into `set_table_name` method in the model is in the _OWNER.TABLENAME_ format, the following error:

`ActiveRecord::JDBCError: table: owner].[tablename does not exist`

will be thrown when attempting to run a query.  This is due to the fact that the `remove_identifier_delimiters` method is only removing the square brackets at the beginning and end of the string.

Since the method is really only looking for square brackets and double quotes, using the String method `tr` eliminates the need to first do a match then run the results of the match through a conditional.