Implement Member sign up

[Mariatta]

1. Ask for the details (see Create Membership Model #2 )
2. Sign up with GitHub: must connect with GitHub for now. ask for name, and email address.
3. If email not granted from GitHub, ask for it. (for now, require from GitHub)
4. Recaptcha etc
5. Mention that we will review application manually.
6. Send email to new member that we received the application.
7. Send email to admin that we have new application.

[Cheukting]

Make sure to explain the membership application will be reviewed by the Admin so it is recommended that they at lease put a bit about themselves in the bio or at lease link to a social media account so the Admin to get to know them a bit more.