Add an automatic sign-up for new users

[jandevaty]

Add a registration form for new users.
New user will be a "guest" and could ask the admins for another role depending on affiliation.

Form fields:

• full name
• email address
• affiliation (drop-down from existing institutions in DB) and a some possibility to ask for new institution - checkbox will be enough ([ ] I haven't found my institution in the list, please contact me to include my institution in runoffDB)
• purpose of registration (text field)
• checkbox "I have read and understand the Terms and conditions and by signing-up I agree to follow the rules"

[jandevaty]

and of course we need to create the "terms & condittions" but as this issue is not top priority it has time ...