Fixed! This solved the problem for me:
Make Tomcat Ignore Servlet in WEB-INF/LIB
I changed the Kundera dependecy to:
<dependency>
<groupId>com.impetus.kundera.client</groupId>
<artifactId>kundera-cassandra</artifactId>
<exclusions>
<exclusion>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
</exclusion>
<exclusion>
<artifactId>jetty-util</artifactId>
<groupId>org.mortbay.jetty</groupId>
</exclusion>
<exclusion>
<artifactId>jetty</artifactId>
<groupId>org.mortbay.jetty</groupId>
</exclusion>
</exclusions>
<version>2.11</version>
</dependency>