Installer can now update / Fixed database delete issue.

The following changes were made:
- Installation will now have an ID (This helps the installer automatically find KA Lite directory);
- Fixed the error message when you choose to delete database;
- The installer will now check if the database exist and if you choose to keep (update), it will skip data gathering from the user;
- In both cases, the database script will not prompt anymore (All data is passed to the script from the GUI);
- Tested all the cases and everything seems to be working fine (At least on my machine);
- Also did some code cleanup and changes to make it more simple and readable;

This should address issue #24