Revert @eaca75e for amatsuda/kaminari#280 again
Fix coercion error when offset_value is nil

This commit does two things:

* Adds `.offset(0)` when limit is set to `nil` for consistency
* Force-returns `1` for `#total_pages` and `#current_page` when
using `per(nil)`. This avoid "Cannot coerce nil into Fixnum"
errors, and will also prevent "ZeroDivisionError" if
`limit_value` is ever typecast using `to_i`.
Use rdoc markup in code
Merge pull request #325 from frodsan/patch-1

Use rdoc markup in code
Merge pull request #314 from yuki24/followup_to_282

Make Kaminari.config.default_per_page changeable
Merge pull request #320 from bricker/fix_nil_math_errors

Fix coercion error when offset_value is nil
Fix typo: shold -> should
Merge pull request #330 from sorah/patch-1

Fix typo: shold -> should