Remove
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
slf4j-log4j12 is the log4j binding for slf4j you dont need to add another log4j dependency.
Added
Provide the log4j configuration in log4j.properties and add it to your class path. There are sample configurations here
or you can change your binding to
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.6.1</version>
</dependency>
if you are configuring slf4j due to some dependencies requiring it.