#4 Users can sign in

[JL-J]

Pre-requisites
Blocked until https://trello.com/c/ceZ4TLlq/10-users-can-sign-up is complete. You can move to "To do" when that's done.

Importance: High

Acceptance Criteria

When a user hasn't signed in and visits the index of the application:

if they visit another URL, they are redirected to the index
they can see a link to a sign in page which prompts them to enter in their email address and password.
they can only enter valid emails
When they submit their details, they are logged in and redirected to their posts page.

Additional

• [ sign in via github]