Added the get method to the storage medium

src/main/java/de/gnmyt/SQLToolkit/storage/SQLStorageMedium.java

@@ -61,6 +61,16 @@ public abstract class SQLStorageMedium extends SQLTable {
         update().where("keyName", key).delete();
     }
 
+    /**
+     * Gets the value of a key
+     *
+     * @param key The key of the value you want to get
+     * @return the value you want to get
+     */
+    public String get(String key) {
+        return select().where("keyName", key).getResult().getString("value");
+    }
+
     /**
      * Gets all entries from the storage medium
      *