Fix. UnicodeDecodeError

Askbot raised an error when i was trying to edit forum settings.

> UnicodeDecodeError at /askbot/settings/EMAIL/
> 'ascii' codec can't decode byte 0xd0 in position 0: ordinal not in range(128)
> Request Method:	GET
> Request URL:	askbot/settings/EMAIL/
> Django Version:	1.4.5
> Exception Type:	UnicodeDecodeError
> Exception Value:	
> 'ascii' codec can't decode byte 0xd0 in position 0: ordinal not in range(128)
> Exception Location:	askbot/deps/livesettings/values.py in _default_text, line 252

I patched it a little.