Rough draft of post on ASP.NET vNext

This is how I typically write my posts. This is a brain dump with
the gist of what I write.

Then I step away, ask for feedback, and then come back and write it
much better.
Tighten up the post
better similes
More tightening. Better analogies
Tone down back compat challenge
Tone it even more
Merge pull request #120 from Haacked/backcompat-siren-song

Rough draft of post on ASP.NET vNext