Changed returned value form EMongoDocument::search() method to match …

…Yii default behavior

Now search() method returns DataProvider instead of $this,
that was incostintent with standard Yii AR

EMongoDocument.php

@@ -1281,7 +1281,7 @@ public function search($caseSensitive = false)
 
 		$this->setDbCriteria($criteria);
 
-		return $this;
+		return new EMongoDocumentDataProvider($this);
 	}
 
 	/**