Release 0.8.0

This is a maintenance release that drops the esoteric JARA completely, updates and modernizes project build process and brings a contractual improvement to map.get (return of default values is now guaranteed).

Resolved issues:
https://issues.carrot2.org/projects/HPPC/versions/12628
JavaDoc:
http://carrotsearch.github.io/hppc/releases/0.8.0/api