[SPARK-959] Updated SBT from 0.13.1 to 0.13.2

JIRA issue: [SPARK-959](https://spark-project.atlassian.net/browse/SPARK-959)

SBT 0.13.2 has been officially released. This version updated Ivy 2.0 to Ivy 2.3, which fixes [IVY-899](https://issues.apache.org/jira/browse/IVY-899). This PR also removed previous workaround.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #426 from liancheng/updateSbt and squashes the following commits:

95e3dc8 [Cheng Lian] Updated SBT from 0.13.1 to 0.13.2 to fix SPARK-959