Change to log4j as default logging library.

Add libs/ for non-maven usage.

Author: Javen

libs/gson-2.2.4.jar

@@ -61,11 +61,16 @@
 			<artifactId>slf4j-api</artifactId>
 			<version>1.7.5</version>
 		</dependency>
-		<dependency>
-			<groupId>ch.qos.logback</groupId>
-			<artifactId>logback-classic</artifactId>
-			<version>1.0.13</version>
-		</dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>1.2.16</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-log4j12</artifactId>
+            <version>1.7.5</version>
+        </dependency>
 
 	</dependencies>