links for related generic objects implemented

Found your app useful but generic relations was missing.
Think it will be usefull for all and implemented it.

Cache used. Defauls:
getattr(settings, 'RELATIVES_CACHE_KEY', 'relatives_cache')
getattr(settings, 'RELATIVES_CACHE_TIME', int(60*60*24))

Also:
1. Template was updatedф and now it's more presentable.
2. Styles were moved to separate css file, placed as usually in 'static' dir.

Hope u like it :)