Same as https://github.com/atom/atom-shell/pull/867

Indeed there are two places worth changing. After these two changes i am able to build Atom-Shell using Pyhon installed by default (without adding to paths)
Merge pull request #83 from IgorKlopov/patch-1

Same as https://github.com/atom/atom-shell/pull/867
Fix the default framework name to be 'Product Framework.framework', not 'Product.framework'
Merge pull request #85 from paulcbetts/default-framework-name

Fix the default Framework name