hint at correct form of social links.

[mlisbit]

When adding a social link to your profile (facebook, github, linkedin, etc), and it's not in the form of http:github.com/, the link will not work. Either correct this via:

• placeholder text
• don't allow submission of form until it's correct, and show warning (maybe through Django form validation).
• have a back-end function that will correct this at run time (disadvantage: non standard inputs in database, and slower)