Tidying up

Profuse apologies for the lateness on such a small commit. Been distracted by school and bands... These two commits (and a third merging back parallel changes in the master branch) address some hiccoughs when using ndn-js via browserify. 

DataUtils: by overwriting JS native toString method on the constructor, Browserify exports a typeError string instead of the Datautils object. simple fix is to declare and export Datautils as an object instead of a 'class', since all the methods are static anyway.

Face/Transport: a simple "ImportFace" method is attached to the transport to get Face declared inside the scope of the transport module, otherwise makeshuffleGetHostandPort throws an error. Trying to import Face via Browserify creates a circular dependency.