Revert "Renamed to main.php" because that's a no no

This reverts commit ece4df7312f0391b168eaca522ea3df8f0c00dfc.
Separating the public assets from the private

Moving all public assets (css, images, index.html) to a sub-directory so
that the private components are not accessible to the public
Adding separate configuration file

Storing the connection parameters in a separate configuration file for
security and accessibility
Creating a configuration container

This file will serve as a configuration validator and parser for the new
configuration file
Updating the database class to use the config file
Updating the application to use the config file