[Build] Fix passing of args to sbt

Simple mistake, simple fix:
```shell
args="arg1 arg2 arg3"

sbt $args    # sbt sees 3 arguments
sbt "$args"  # sbt sees 1 argument
```

Should fix the problems we are seeing [here](https://amplab.cs.berkeley.edu/jenkins/job/Spark-Master-SBT/694/AMPLAB_JENKINS_BUILD_PROFILE=hadoop1.0,label=centos/console), for example.