Isolation of the I18n.t

Hi Jose,

I've isolated the 
    I18n.t

method in order to be able to implement alternate translation schemes.

I'm not ready to use 4.0.0.beta1 yet - hence the pull request for 2.0 <:)

(but the change for 4.0 really is the same)

the alternate scheme I've implemented is https://github.com/wdiechmann/i18n-active_record

cheers
Walther