Change sourcing scripts to mimic Bash more closely
Change sourcing scripts to mimic Bash more closely

Summary:
Always load /etc/profile and then pick one of .bash_profile, .bash_login, and .profile.

See http://superuser.com/a/357175/54080

Test Plan: Ran both scripts and didn't get an error.

Reviewers: jesse

Differential Revision: D3020

fbshipit-source-id: 3f4045a

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