Update Boost for unique_ptr

This branch adds the necessary header files to our local Boost distribution to enable the use of Boost's C++03-compatible unique_ptr implementation.  

C++11's std::unique_ptr is a potential non-deprecated drop-in replacement for libMesh's AutoPtr implementation.  In the meantime, boost::interprocess::unique_ptr might serve as a useful fallback for compilers that don't yet support C++11 std::unique_ptr.  I've tested this on the compilers I have readily-available (GCC 4.6.x and 4.7.2, Clang 3.3, Intel 12) and our simple test_boost.cc code seems to work, but each compiler required a slightly different subset of the boost header files, so I'm not ready to say this support is particularly robust yet.

@roystgnr or anyone else who has time to try out this branch on some other compilers, I'd really appreciate it.  Basically after 'make installing' libmesh, set your `LIBMESH_DIR`, and go to the contrib/boost in the top level (not build!) directory and run
```
make -f Makefile.test_boost test_boost
```
and let me know if it compiles successfully.