remove pluralize, add its functionalities to t

`t` now accepts, as a second parameter, a number as a shortcut to `{smart_count: theNumber}`. The feature of `pluralize` that reads an object's length is removed, as passing the explicit form `obj.length` looks better.
update docs to match the change to t

- Also noticed inconsistencies in tab/space in README, replaced the few tabs into space.

- Slight precision on phrases.
add pluralization tests back
update readme tests
Merge pull request #7 from chenglou/new-t

remove pluralize, add its functionalities to t