Included std::tuple or boost::tuples::tuple within a tuples namespace of stout.

Namespace pull-in of std::tuple or boost::tuples::tuple, depending on
the availability of C+11. The results are part of a tuples namespace
of stout.

Example usage including fully qualified namespaces:

tuples::make_tuple(42, true); int foo = tuples::get<0>(tuple);

Review: https://reviews.apache.org/r/18360