HOTFIX: Add This Integration Updates

Updated the default AddThis code to use their newest default code.
Switched out the static icon sets to use their “preferred icons”
http://support.addthis.com/customer/portal/articles/381263-addthis-client-api#rendering-preferred-services

This means that the icons can change from user to user depending on browsing/sharing habits.

Also, if they have an AddThis account, analytics can be enabled by entering their Profile ID which can be found here: https://www.addthis.com/settings/publisher

New look

Also updated the wording on the Theme Settings to say Profile ID instead of Username