vibe.d in techempower web framework benchmark

[deadalnix]

I have been discussing with the author of techempower web 
framework benchmark. He ended asking me a pull request to 
integrate vibe.d .

See :
http://www.techempower.com/benchmarks/

The instruction to create a pull request are here : 
https://github.com/TechEmpower/FrameworkBenchmarks

I don't have much time right now, so if someone want to do it, 
that would be awesome. If nobody volunteer, I'll do it, but I 
clearly lack time right now. I also lack knowledge about how to 
get the best out of vibe.d and risk to propose an under 
performant pull request.

vibe.d perform very well in many situation, so I think this is a 
good opportunity to demonstrate what we have and do some 
advertisement for D.