Make it easier to sign up with correct full name

[tinaroh]

It's easy to enter a less-than-ideal full name if the linked account doesn't have the user's real name. We should add some text to encourage users to sign up with full name. e.g. "We imported your name from your account. Please double-check to make sure it's your full name and spelled correctly!"

We can also add tooltips with validations when we think that something's wrong:

• First and last name are capitalized ("john doe")
• First and last name are more than one character each ("John D")

[tinaroh]

Deprecating web app and we don't pull from Google/Facebook anymore.