Revert "Upgraded avocado to spark 0.9.0 and scala 2.10.3. On the way, fixed a few small bugs."

This reverts commit d311aac8210c67d439ca7413226dfd98397d5873.
Merge pull request #16 from bigdatagenomics/revert-spark-0.9

Reverts upgrade to spark 0.9.0