mrf.js :: change return types and expectations

 - flatten looks through children to build obj row
lib/stats.js :: handle new return type
lib/today.js :: return object not array which matches header
lib/sum.js :: mrf to group on tag and sum durations
package.json :: depend on underscore
merge :: refactor mrf return types and add sum.js

* tab:
  package.json :: depend on underscore
  lib/sum.js :: mrf to group on tag and sum durations
  lib/today.js :: return object not array which matches header
  lib/stats.js :: handle new return type
  mrf.js :: change return types and expectations
package.json :: ~wordwrap
package.json :: use mimetnet/cli until chriso/cli pulls request