As a campaigner (editor) I want to be able to display the total number of petition signups in my basket (for example Forests or Oil), not just the signups of my specific push.

Example: the People vs Oil petition will be an umbrella petition which will display the total number of signups from different sub-petitions. Maybe if we could add tags to petitions then we can just display the total signups from petitions with that tag.

Requirements: web editors can specify which global campaign their campaign page is related to. The counter will then show the total number of signups from that campaign instead of the number of signups that happened only on the specific petition.