Ensured ExecutorInfo.framework_id is set.

This includes an update to the Scheduler Driver to set framework_id
on launchTask requests, as well as a change to the Slave to set
framework_id when generating ExecutorInfos for Command Executors.

Review: https://reviews.apache.org/r/13455
Fixed typos in scheduler.hpp and test_framework.py.

From: Yashwanth Nannapaneni <yashwanth620@gmail.com>
Review: https://reviews.apache.org/r/13448
Updated glog to 0.3.3.

This fixes a build issue with clang.

From: Vinson Lee <vlee@freedesktop.org>
Review: https://reviews.apache.org/r/13473
Revert "Fixed master to send a FrameworkReregistered message when the
framework re-registers with a failed over master."

This reverts commit 68ccbf1d9ab1fee2bef933a27368e5460f9be42e.

Review: https://reviews.apache.org/r/13538
Added checkpointing ability for example frameworks.

Review: https://reviews.apache.org/r/13398
Fixed slave to not re-register with master in cleanup mode.

Review: https://reviews.apache.org/r/13442
Improved the allocator to not offer non-checkpointing slave resources
to checkpointing frameworks.

Review: https://reviews.apache.org/r/13407
Fixed slave to always delete the latest slave symlink on
shutdown or cleanup.

Review: https://reviews.apache.org/r/13392
Added fs::size() to calculate the total disk space
and killed fs::available().

Review: https://reviews.apache.org/r/13394
Fixed slave to offer total disk by default.

Review: https://reviews.apache.org/r/13395
Changed slave state recovery to ignore absence of files as safe.

Review: https://reviews.apache.org/r/13443
Fixed master to properly handle TASK_LOST updates generated by it.

Review: https://reviews.apache.org/r/13446
Fixed slave to not recover terminated executors.

Review: https://reviews.apache.org/r/13450
Fixed cgroups isolator to do setsid on the executor process.

Review: https://reviews.apache.org/r/13449
Improved task validation error messages in master.

Review: https://reviews.apache.org/r/13454
Implemented a LinkedHashMap that preserves the insertion
order of keys of a hashmap.

Review: https://reviews.apache.org/r/13464
Fixed slave to use LinkedHashMap to store tasks.

Review: https://reviews.apache.org/r/13485
Fixed executor driver to store tasks and updates in LinkedHashMap.

Review: https://reviews.apache.org/r/13486
Fixed slave to not re-register with Command Executors.

Review: https://reviews.apache.org/r/13487
Fixed slave to always call Isolator::resourcesChanged() when an
executor re-registers.

Review: https://reviews.apache.org/r/13503