Fix typo on README
Add method 'to_time'

Now it's possible to convert a Nostradamus object to a time object.
Refactor method 'to_time' to return a localized datetime object

Added active support as a dependency to use the 'Time.zone.local' api
that returns a localized datetime object.
Update dependencies to work with rails 3.2.6

Downgrade versions of activesupport and tzinfo to work with rails 3.2.6