Add application category (Utilities)

OS X's View by Category requires LSApplicationCategoryType otherwise it sorts an app out to "Other" at the bottom.

Utilities was chosen, Apple's other categories are here: https://developer.apple.com/library/ios/documentation/general/Reference/InfoPlistKeyReference/Articles/LaunchServicesKeys.html#//apple_ref/doc/plist/info/LSApplicationCategoryType

'public.app-category.productivity' would be my second choice but I don't have a strong preference.