inboxsdk types - add 'Instance' to main interfaces
inboxsdk types - add 'Instance' to main interfaces

borisyankov/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,borisyankov/DefinitelyTyped,AgentME/DefinitelyTyped,AgentME/DefinitelyTyped,markogresak/DefinitelyTyped,AgentME/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped