Add registration feature

[tkrille]

Users should be able to register an account with OSIAM by themselves. This feature should be working more or less like the existing registration of the Add-On Self Administration. I think the following key features are a must have for the first version:

• Turn the feature on and off
• Configuration whether the username is the same as the email address
• Changing the registration page template, using at least the following fields
  • username
  • email address, with optional re-enter
  • password, with optional re-enter
  • real name, i.e. first and last name or both
• Verify the given email address, if any

Anything else should be added in additional issues.

Part of #158

[dacrome]

+1
But the registration is possible with all fields of a SCIM user? What about extensions?

[tkrille]

I think we should agree on the most important fields, e.g. username, email, password. If an application needs more data from a user, before they can do something with it, it should ask the user for this information, e.g. when they first login.

[dacrome]

But if we copy the code from the self-administration we can provide the registration endpoint which accepts all scim user fields.

[tkrille]

I'm not sure yet, whether we will just copy the current code. But if we do, then, yes, we will copy the complete feature set.

[dacrome]

The one who adds this feature, please beware of this feature: osiam/addon-self-administration#67