HUE-2047 [oozie] Clicking on workflows only works for first page of Workflow Manager

Fixed all the other pages too
HUE-1660 [core] Export/import all stored scripts

Use jsonpickle libraries for serialization.
Create hierarchy of relationships by providing wrapper objects that store
m2m, m2o, and gfk information.

Add 'filename' and 'filedata' hooks so that users have files that can be
modified.