Adding sudo to express install

npm install -g express would not run without the sudo command in front.
named the function 'home' but referred to it in the directions as 'welcome'
Deleted unnecessary 's' from the word 'commas'.  Simple grammar correction.
correcting the spelling of 'templating'.
More specific instructions for where to add the next line of code.
adding link to handlebars library to explain the directory structure.
Grammar correction.  Fixing a run-on sentence.
spelling correction
Merge pull request #3 from ryanrombough/master

Adding sudo to express install