Interest: Add copy constructor.
Face: In expressInterest, support onData and onTimeout callbacks.  Support but deprecate using Closure. Refs #1073.
expressInterest: Add TODO for changing to expressInterest which uses callbacks, not Closure. Refs #1073.
Merge branch 'issue/1073-callbacks-in-expressInterest'. Refs #1073
http://redmine.named-data.net/issues/1073