Unfortunately i'm not shure how to do it in right roundup way.

1. About date.py.

I didn't catch where Date objects are created. So i don't know how to 
pass "translator" to them.

2. About i18n.py module. Make it sense tracker language setting.  
(quick fix)

It will sense setting if we replace
def get_translation(language=None, ...
to 
def get_translation(language=tracker.config["language"], ...

The problem is that there is no global variable of tracker instance 
("tracker"). It located somewhere in startup shell like roundup-server. 
The worse is if we'll add global tracker variable in instance.py we get 
circular reference.
So i don't know how to get tracker setting in i18n.py.