Add clean to build

dev/run-tests

@@ -62,7 +62,7 @@ echo "========================================================================="
 # echo "q" is needed because sbt on encountering a build file with failure 
 # (either resolution or compilation) prompts the user for input either q, r, 
 # etc to quit or retry. This echo is there to make it not block.
-echo -e "q\n" | SPARK_HIVE=true sbt/sbt assembly | \
+echo -e "q\n" | SPARK_HIVE=true sbt/sbt clean assembly | \
   grep -v -e "info.*Resolving" -e "warn.*Merging" -e "info.*Including"
 
 if [ -n "$run_sql_tests" ]; then