Refactor update obsolete code comment
Fix uncomplete `fallback_to_devise` option doc.
Refactor use .exists? when checking token existence

Fixes #55
Add :only, :except filter options documentation
Add failing scenarii
Add :only and :except filter options

Allows the `acts_as_token_authentication_handler_for` to be
applied to a specific set of controller actions, as would a filter.

Fixes #53
Closes #62
Update doc/features.html
Merge branch 'add-only-except-filter-options'
Bump version number