Removed unnecessary instruction.
Create separate instruction

I'm not sure if this step is needed, but it existed before. If it is 
needed we should include WHY you have to do this.
Ensure that node is 32bit on win32
Make sure python2.7 is installed on win32

Closes #2193 
Closes #2167
Closes atom/node-runas#5
Remove unnecessary instructions
Update windows build instructions
Require `fs` in bootstrap
Upgrade to grunt-download-atom-shell@0.7.1
Troubleshooting message no longer needed because of 
50a616d91cc5504b9c4daac3156d6ca0598
Merge remote-tracking branch 'origin/master' into cj-windows-build-instructions-update

Conflicts:
	script/bootstrap
Don't require 32bit node
Upgrade to grunt-download-atom-shell@0.7.2
Don't preserve rows when scrolling
Overdraw lines to discourage Blink from repainting the entire editor
Update scroll position directly on mousewheel events

Previously, we were updating the scrollbars and relying on an async
scroll events to fire. But updating the scrollbars is expensive, so this
updates the model directly when the next animation frame fires instead.
Measure characters in new lines when vertically scrolling stops
Give each line its own layer on the GPU
Drop lineOverdraw and scroll-view-content div
Render each line number on its own layer
Manually set the gutter width to the width of a line number

We need to absolutely position line numbers to minimize repaints, but
the gutter needs to be wide enough to show them.