add component.json

Again sorry for my previous comment, didnt mean to be rude
I was just surprised that the file had been renamed since I orignally added this file to work with component (https://github.com/SlexAxton/messageformat.js/pull/17)

I tried to add a simple symbolic link but it didnt not work, cause component installer try to fetch https://raw.github.com/pgherveou/messageformat.js/master/component.json and with a symlink the content of this url would not what we need.

So i just did a copy of bower.json, Hope its cool for you to keep both files in the repo...