Add exec-path-from-shell to core.
On OS X, an Emacs instance started from the graphical user interface will have a different environment than a shell in a terminal window.
This library works around this problem by copying important environment variables from the user's shell.
URL : https://github.com/purcell/exec-path-from-shell
Merge pull request #8 from firesofmay/master

Add exec-path-from-shell