Revert "Preparing development version 1.2.1-SNAPSHOT"

This reverts commit fc7bff00ac731d2632213a98cd92dc5e84ce7dcd.
Revert "Preparing Spark release v1.2.0-rc1"

This reverts commit 39c7d1c1f9a7785285cf4c20dfbffd96f72d5634.
Updating version in package.scala