Add pre email confirmation module

[mconf-daileon]

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Author Name: Lucas Zawacki (Lucas Zawacki) Original Redmine Issue: 1669, http://dev.mconf.org/redmine/issues/1669 Original Date: 2015-06-26

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So users can only create an account after they have confirmed their email:

• User tries to create an account and enters some basic data (email, login, data from shibboleth, ldap, ...)
• Server creates a new request with the data, email and a unique secret token
• Sends an email with the secret token
• User uses the secret token as an extra field on the registration form where he can put the rest of his data and create the account
• Account is created as confirmed