[boost] NT2 and Boost.SIMD beta 2 available

This following releases updates NT2 and Boost.SIMD libraries.10 months had past and 176 Issues have been closed since last beta release and more than 2000 commits have been issued. Boost.SIMD is heading toward API stability. We want to tackle ons ome more compile time issues before going for an actual Boost Review. Special thanks to Tim Blenchmann and Domagoj Saric for their help and suggestions throughout this development. The release Changelog is here : https://github.com/MetaScale/nt2/releases The files can be download from : http://nt2.metascale.org/downloads/ The Documentation (in progress) is here : http://nt2.metascale.org/doc/html/index.html