Fix: PostClustering with Boost 1.56+ on systems w/o BALL_HAS_NOEXCEPT
Fix: PostClustering with Boost 1.56+ on systems w/o BALL_HAS_NOEXCEPT

Boost 1.56+ implicitly deletes the copy constructors of `stored_edge_properties`. In
order to automatically use the respective move constructor instead, ClusterProperties
has to be _nothrow_ move constructible!

tkemmer/ball,tkemmer/ball,tkemmer/ball,tkemmer/ball,tkemmer/ball,tkemmer/ball