Move social link generation into the user model property social_links. Convert all uses of personal_site to personal
Merge branch 'develop' of https://github.com/CenterForOpenScience/osf.io into feature/unified-social-links
Load social from SOCIAL_FIELDS constant rather than writing each line out
More null checks
Add tests for unified social links
Merge branch 'feature/unified-social-links' into develop