Updated slave and master to use lambda:: consistently.

From: Ian Downes <idownes@twitter.com>
Review: https://reviews.apache.org/r/13784
Fixed a 32 bit compilation issue in files.cpp.

The call to min(ssize_t, long int) won't compile on 32 bit systems
because ssize_t resolves to int on those systems.

From: Kevin Lyda <kevin@ie.suberic.net>
Review: https://reviews.apache.org/r/13793
Upgraded ZooKeeper from 3.3.4 to 3.3.6.

From: Vinson Lee <vlee@twitter.com>
Review: https://reviews.apache.org/r/13598