Cannot create new `Tag()` element with non-empty attrs and no builder

[Martijn Pieters]

The `Tag.__init__` method assumes that `builder` is always set when you pass in attributes:

>>> from bs4 import Tag
>>> Tag(name='div', attrs={'id': 'foo'})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/mj/Development/venvs/stackoverflow-2.7/lib/python2.7/site-packages/bs4/element.py", line 762, in __init__
    elif attrs and builder.cdata_list_attributes:
AttributeError: 'NoneType' object has no attribute 'cdata_list_attributes'

This is caused by:

        if attrs is None:
            attrs = {}
        elif attrs and builder.cdata_list_attributes:
            attrs = builder._replace_cdata_list_attribute_values(
                self.name, attrs)
        else:
            attrs = dict(attrs)

while later in the method `builder` is not assumed to be always set:

        if builder is not None:
            builder.set_up_substitutions(self)
            self.can_be_empty_element = builder.can_be_empty_element(name)
        else:
            self.can_be_empty_element = False

I've attached a simple patch.

[Leonard Richardson (leonardr)]

OK. I can't guarantee there won't be subtle bugs if you introduce a Tag created with no builder to a normal BeautifulSoup object, but I agree it shouldn't crash immediately.