title: an error in spark sbt assembly
body: <p>In spark installing README,I write command './bin/spark-shell',
  I got some hint follwing:</p>
  
  <p>Found multiple Spark assembly jars in /opt/spark-0.9.0-incubating-bin-hadoop1/assembly/target/scala-2.10:
  spark-assembly-0.9.0-incubating-hadoop1.0.4.jar
  spark-assembly_2.10-0.9.0-incubating-hadoop1.0.4.jar
  Please remove all but one jar.</p>
  
  <p>I ever try to remove one of them ,but I fail to success.
  If somebody can deal with it ,please tell me.
  thanks. </p>