fix to_display when bip_value is undefined/null
Merge pull request #384 from seuros/bipnull

fix to_display when bip_value is undefined/null
Converting attr(data) to data()
Merge pull request #391 from bensaufley/master

Converting attr(data) to data()
removed duplicate trim method call. Added a spec to test response being nil from display_as method
moved from javascript to capybara click on the page.
Merge pull request #392 from faheematapoex/tests_for_display_as_being_nil

Tests to display the default em-dash when display_as returns nil
add DisplayMethods even for empty values, fix for #229
add DisplayMethods even for empty values, fix for #229