How to Automatically Make All post images the same size

One of my favorite sites I bookmark for code snippets was down today (insert curses here) and I was back to square one with finding out how to do something… that something was making all of the images in Blogger posts the same size… with the exception of the Pinterest pin it button – how awful is it when you resize your images and your pin it button is enormous?!?!
Very awful indeed.
So if you ever wondered how to make this happen, here is the code you need to slip in to your template to make all of your images the same width, sans the pin it button: