Clean-up drafts

[samans]

• Clean-up and review drafts
  • edit the tree files to include only the branches and leafs necessary (by hand)
  • revisions of the imports and references
  • clean up any idnits (copyright dates, boiler plate)
  • ensure the rfcstrip for yang files produces yang files that validate with pyang
  • ensure the version numbering of the yang files is correct