Updated Config for New Database Configuration

Accomodating changes in the way Database objects are instanciated.
Cleaned up Nav config too.
Changed the Initial Sequence when config is Loaded
Removed Unnecessary Nav Config Option

Default page was a option in the nav_config, but unneeded because of the
DEFAULT_PAGE constant.
Removed default_page Property from Nav.php
Checking Validity of Database Queries

The query method now checks that a valid PDO::Statement is returned from
PDO queries; returns false otherwise.

The select method checks that select queries return valid response.