Fixed master to correctly terminate the non-checkpointing framework's
tasks, when a slave disconnects.

From: Brenden Matthews <brenden.matthews@airbnb.com>
Review: https://reviews.apache.org/r/11128
Upgraded libev to 4.15.

Review: https://reviews.apache.org/r/11289
Fixed python setup.py to use libev-4.15.

Review: https://reviews.apache.org/r/11290