Update README to better match backbonejs.org 

line 14 readme missing the word "with":
Backbone supplies structure to JavaScript-heavy applications by providing models key-value binding and custom events, collections...
--> on backbonejs.org reads as -->
Backbone.js gives structure to web applications by providing models with key-value binding and custom events, collections...

Also bolded models, views and collections just as they are on backbonejs.org
removed the strong tags, but kept the "with" on 14
Merge pull request #3318 from NickStefan/patch-1

Update README to better match backbonejs.org