#87 breaks persistent Text fields

[agroszer]

We persist some schemas that use fields. Setting unicode_normalization in Text.__init__ breaks persistent loading of such schemas.

[jamadden]

IIUC, a class attribute would solve that?

class Text(MinMaxLen, Field):
    unicode_normalization = 'NFC'

    def __init__(self, *args, **kwargs):
        self.unicode_normalization = kwargs.pop(
            'unicode_normaliaztion',
            type(self).unicode_normalization)
        super(Text, self).__init__(*args, **kwargs)