Upgrade to pants 1.2.0rc0.
Upgrade to pants 1.2.0rc0.

This pulls in support for OSX Sierra.
Release notes are here: http://pantsbuild.github.io/notes-master.html

Reviewed at https://reviews.apache.org/r/52640/

crashlytics/aurora,thinker0/aurora,rdelval/aurora,apache/aurora,crashlytics/aurora,rdelval/aurora,apache/aurora,medallia/aurora,crashlytics/aurora,thinker0/aurora,crashlytics/aurora,apache/aurora,apache/aurora,crashlytics/aurora,rdelval/aurora,thinker0/aurora,rdelval/aurora,medallia/aurora,rdelval/aurora,thinker0/aurora,crashlytics/aurora,medallia/aurora,apache/aurora,apache/aurora,medallia/aurora,rdelval/aurora,medallia/aurora,thinker0/aurora,medallia/aurora,thinker0/aurora