Move emailaddress model to Colab

[chaws]

In colab-superarchives-plugin/src/colab_superarchives/models.py there is:
class EmailAddressValidation(models.Model):
address = models.EmailField(unique=True)
user = models.ForeignKey(settings.AUTH_USER_MODEL, null=True,
related_name='emails_not_validated')
validation_key = models.CharField(max_length=32, null=True,
default=get_validation_key)
created = models.DateTimeField(auto_now_add=True)

class Meta:
    unique_together = ('user', 'address')

@classmethod
def create(cls, address, user):
    email_address_validation = cls.objects.create(address=address,
                                                  user=user)
    return email_address_validation

@classmethod
def verify_email(cls, email_address_validation, verification_url):
    return email.send_verification_email(
        email_address_validation.address,
        email_address_validation.user,
        email_address_validation.validation_key,
        verification_url
        )

and others related to email. Move those to Colab core.

[lucaskanashiro]

@lucasmoura and I started to work in this issue, branch move_emails_models_to_core in colab core. We made a pull request and we are waiting for some review (colab/colab#87). The continuous integration are failing because of a taggit migration and we need to investigate how to fix it (in my devel environment everything works well). @chaws could you finish this issue? =)

[chaws]

Sure @lucaskanashiro , I was away last week, but will continue these tasks soon.