Upgraded libprocess to protobuf 2.5.0.

Review: https://reviews.apache.org/r/16651
Upgraded stout to protobuf 2.5.0.

Review: https://reviews.apache.org/r/16652
Upgraded Mesos to protobuf 2.5.0.

Review: https://reviews.apache.org/r/16653
Replaced 'std::tr1' with 'lambda' and 'memory' in stout.

The 'lambda' and 'memory' namespace gives us a level-of-indirection
that makes it easier to do either C++03 or C++11 compilation.

Review: https://reviews.apache.org/r/16654
Replaced 'std::tr1' with 'lambda' and 'memory' in libprocess.

Some fixes and enhancements were also made to the C++11 version of the
library. At this point libprocess can be compiled for C++11 and all
tests pass with gcc 4.8.

Review: https://reviews.apache.org/r/16655
Replaced 'std::tr1' with 'lambda' and 'memory' in Mesos.

At this point we can compile Mesos for C++11 with gcc 4.8.

Review: https://reviews.apache.org/r/16656
Upgraded to ZooKeeper 3.4.5.

In order to build Mesos with clang we need to upgrade
ZooKeeper. Unfortunately, Mesos leveraged some internal APIs of
ZooKeeper that changed so this commit required some refactorings.

Review: https://reviews.apache.org/r/16657
Added a patch for glog required when compiling with clang.

Review: https://reviews.apache.org/r/16658
Fixed warning given by clang.

Review: https://reviews.apache.org/r/16659
Fixed protobuf::read bug exposed when running Mesos compiled by clang.

Review: https://reviews.apache.org/r/16660
Refactorings necessary for getting clang to compile C++11 libprocess.

A test was also added that provides all possible examples of using
std::bind and lambda's with process::defer, Future::on* (Ready,
Failed, etc) and Future::then.

Review: https://reviews.apache.org/r/16661
Refactorings necessary to get Mesos to compile with clang.

Review: https://reviews.apache.org/r/16662
Added --with-cxx11 to libprocess configuration.

When building with clang we assume --with-cxx11. For example:

  CC=/path/to/clang CXX=/path/to/clang++ ../configure

But when building with gcc 4.8 you need to specify C++11:

  CC=/path/to/gcc CXX=/path/to/g++ ../configure --with-cxx11

Review: https://reviews.apache.org/r/16663
Added --with-cxx11 to Mesos configuration.

When building with clang we assume --with-cxx11. For example:

  CC=/path/to/clang CXX=/path/to/clang++ ../configure

But when building with gcc 4.8 you need to specify C++11:

  CC=/path/to/gcc CXX=/path/to/g++ ../configure --with-cxx11

At this point in time compiling using C++11 with gcc 4.8 on OS X does
not work with Python so it is explicitely disabled.

Review: https://reviews.apache.org/r/16664