Remove "urn:uuid:" from UUIDs so they validate with FHIR validator

[Brian Cragun]

Describe the bug
UUIDs of form "urn:uuid:" now fail in the latest FHIR validator.

"severity" : "error",
  "code" : "structure",
  "details" : {
   "text" : "UUIDs must be valid"
  },
  "expression" : ["Bundle.entry[0].fullUrl"]

To Reproduce
Run any current output of the converter through the FHIR validator.

Expected behavior
UUIDs should validate

[Lisa Wellman]

In Release 1.0.13