Merge pull request #16 from thisislawatts/master

Adds back in ajax functionality for the widget (thanks, @thisislawatts!)
Adds check for id attribute when WPP's widget is ajaxified
Removes hardcoded plugin's slug on translation strings
Fixes duplicate ajax hook for widget
Renames ajax_get_popular to simply get_popular
Removes colon, it can instead be added via CSS :after