Implementing the Database class.

* Updated the Database class to work like a Singleton with a getInstance() method.

 * The Database class does not have a private constructor so it can still be instantiated in case someone needs to do so.

 * Replaced Logger class with Log class.

 * Updated Module to have an instance of the Database object as well as the Model class.

 * In my perfect vision for usage, the Module classes should never talk directly to the database, but do so via Models, but I know that's asking a lot, so I'm leaving in some options for folks.

 * Updated documentation.

classes/Database.php

@@ -25,6 +25,19 @@
  */
 class Database extends Object
 {
+	/**
+	 * Instance of the Database object
+	 *
+	 * Within the PICKLES system, the database instance is shared, but the
+	 * Database constructor is not private, just in case someone wants to
+	 * create new Database objects.
+	 *
+	 * @static 
+	 * @access private
+	 * @var    object
+	 */
+	private static $instance;
+
 	/**
 	 * Hostname for the MySQL Server
 	 *
@@ -114,6 +127,25 @@ class Database extends Object
 		}
 	}
 
+	/**
+	 * Get instance of the object
+	 *
+	 * Instantiates a new object if one isn't already available, then
+	 * returns the instance.
+	 *
+	 * @static
+	 * @return object self::$instance instance of the Database 
+	 */
+	public static function getInstance()
+	{
+		if (!isset(self::$instance) || empty(self::$instance))
+		{
+			self::$instance = new Database();
+		}
+
+		return self::$instance;
+	}
+
 	/**
 	 * Opens database connection
 	 *
@@ -180,7 +212,7 @@ class Database extends Object
 	public function execute($sql, $input_parameters = null)
 	{
 		$this->open();
-
+		
 		Log::query($sql);
 
 		// Checks if the query is blank