Create database automatically on installation

[jeffzemla]

The installation requires you to manually create a database in SQL, which it will then populate with the proper schema. This can be done automatically in SQL. The user shouldn't have to know how to create an SQL database in order to install TurkGate.

Specifically:

1. If database does not exist, create it and populate database.
2. If database exists but is empty, populate database.
3. If database exists and is already populated, flag a warning. Currently, install.php will report "Installation successful!" if the database and table already exist, despite not actually doing anything. This is problematic if the table is corrupted.