Exposed recovery errors that are encountered in non-strict
recovery mode.

Review: https://reviews.apache.org/r/13789
Added "SlaveRecoveryTest.MasterFailover" test.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/13747
Added SlaveRecoveryTest.MultipleFrameworks test.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/13786
Added a slave recovery test for the case of multiple slaves.

From: Jie Yu <yujie.jay@gmail.com>
Review: https://reviews.apache.org/r/13753
Added a recovery timeout for executor driver self-termination.

Review: https://reviews.apache.org/r/13791
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
Merge branch 'master' into master-sonar