screen for sign-up/log-in

user sees a "mission statement"/ app description with sign up form below
|      |
|      |
|      user enters email, password, submit--------------------------- >  homepage
|      |
|      |
|      |
|      v                                                                   ^
|      user enters invalid credentials ----> error message                 |
|       ^                                                                  |
v       |                                                                  |
user already has account so they log in from the top of the page-----------|