Updated registration email templates.

* Changes to helpers probably wasn't necessary. I was looking at it to find out what templates were used by the send_email function. I do think the change is clearer, though.
* for the password reset email, we could probably just pass in site as a context variable, but I did it this way so that it was explicit what I was after. Once we decide which context to pass in, we should be ok.
Don't know. Not sure it matters either:
```python
>>> unicode("Estée Lauder")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 3: ordinal not in range(128)
>>> 
```