Fix encoding related errors that prevent the BrowserIDRegisterForm to properly render.

Also removed a |safe filter as the form field is already considered safe content.

Here's a traceback that shows the error:

    Traceback (most recent call last):
      File "/usr/lib/python2.6/wsgiref/handlers.py", line 93, in run
        self.result = application(self.environ, self.start_response)
      File "/home/vagrant/src/vendor/src/django/django/contrib/staticfiles/handlers.py", line 67, in __call__
        return self.application(environ, start_response)
      File "/home/vagrant/src/vendor/src/django/django/core/handlers/wsgi.py", line 241, in __call__
        response = self.get_response(request)
      File "/home/vagrant/src/vendor/src/django/django/core/handlers/base.py", line 177, in get_response
        response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
      File "/home/vagrant/src/vendor/src/django/django/core/handlers/base.py", line 109, in get_response
        response = callback(request, *callback_args, **callback_kwargs)
      File "/home/vagrant/src/apps/sumo/decorators.py", line 15, in _checkssl
        return view_func(request, *args, **kwargs)
      File "/home/vagrant/src/vendor/src/django/django/views/decorators/debug.py", line 75, in sensitive_post_parameters_wrapper
        return view(request, *args, **kwargs)
      File "/home/vagrant/src/kuma/users/views.py", line 218, in browserid_register
        {'register_form': register_form})
      File "/home/vagrant/src/vendor/src/django/django/shortcuts/__init__.py", line 44, in render
        return HttpResponse(loader.render_to_string(*args, **kwargs),
      File "/home/vagrant/src/vendor/src/django/django/template/loader.py", line 176, in render_to_string
        return t.render(context_instance)
      File "/home/vagrant/src/vendor/src/jingo/jingo/__init__.py", line 191, in render
        return super(Template, self).render(context_dict)
      File "/home/vagrant/env/lib/python2.6/site-packages/jinja2/environment.py", line 891, in render
        return self.environment.handle_exception(exc_info, True)
      File "/home/vagrant/src/kuma/users/templates/users/browserid_register.html", line 5, in top-level template code
        {% set classes = 'register' %}
      File "/home/vagrant/src/kuma/users/templates/users/base.html", line 2, in top-level template code
        {% set styles = ('users',) %}
      File "/home/vagrant/src/templates/base.html", line 149, in top-level template code
        {% block content %}{% endblock %}
      File "/home/vagrant/src/kuma/users/templates/users/browserid_register.html", line 56, in block "content"
        {{ register_form }}
      File "/home/vagrant/env/lib/python2.6/site-packages/jinja2/_markupsafe/_native.py", line 20, in escape
        return s.__html__()
      File "/home/vagrant/src/vendor/src/jingo/jingo/monkey.py", line 57, in __html__
        return unicode(self)
      File "/home/vagrant/src/vendor/src/django/django/forms/forms.py", line 98, in __unicode__
        return self.as_table()
      File "/home/vagrant/src/vendor/src/django/django/forms/forms.py", line 220, in as_table
        errors_on_separate_row = False)
      File "/home/vagrant/src/vendor/src/django/django/forms/forms.py", line 148, in _html_output
        bf = self[name]
      File "/home/vagrant/src/vendor/src/django/django/forms/forms.py", line 110, in __getitem__
        return BoundField(self, field, name)
      File "/home/vagrant/src/vendor/src/django/django/forms/forms.py", line 405, in __init__
        self.help_text = field.help_text or ''
      File "/home/vagrant/src/vendor/src/django/django/utils/functional.py", line 112, in __wrapper__
        raise TypeError("Lazy object returned unexpected type.")
    TypeError: Lazy object returned unexpected type.