add directions to install express with sudo

I ran into problems installing express globally. The error said I didn't have permission to install it. I have added directions to use sudo in case that happens to others.

I changed Welcome to Home towards the end of Ch 1

Reordered comments when setting up Handlebars so that the comment order matches the code order. 

Added reference to routes.js when we needed to add a line of code to it. I think this helps better clarify where to make this edit.

Sorry about the trailing white space edits. I've updates Sublime so it won't remove trailing white space.