Release 0.9.0.RC2

Release candidate preview for 0.9.0.

Resolved issues:
https://github.com/carrotsearch/hppc/milestone/2?closed=1

JavaDoc:
http://carrotsearch.github.io/hppc/releases/0.9.0.RC2/api/

New features and API changes

• GH-13: Add automatic module name to the generated JAR's manifest ("com.carrotsearch.hppc")

Improvements

• HPPC-191: Improve Accountable implementation (Haoyu Zhai)