Updated dependencies and gemspec to match the latest gem updates
refs #9
Container#field now supports to search for elements with :placeholder. Even though, extending the Watir
attributes for it was rather simple, the solution is not very nice as it gives the :placeholder locator to
ALL HTMLElement sub classes, this should be improved in the near future.
refs #9
Container#fill_in now also uses the placeholder keyword as option.
refs #9
Added short class documentation.
closes #9
Merge branch 'v2.3.0' into 'master'

V2.3.0

added placeholder support for Container#field and Container#fill_in

See merge request !2