Consistency checking and optional fields

• Added GET /admin/version
• Docker tag for exchange docker image no longer has the "v" before the version number
• For the references between resources that are not enforced by DB foreign keys, added checking when the resource is created, updated, or patched:
  • microservices referenced by a workload
  • workloads referenced by a pattern
  • patterns referenced by an agbot
  • pattern referenced by a node
• Made the following resource fields optional:
  • pattern: dataVerification can be omitted or specified as {}
  • microservice: downloadUrl can be omitted, matchHardware can be omitted or specified as {}
  • workload: downloadUrl can be omitted

(No need to upgrade the db if coming from version 1.38 or later, altho it won't hurt either)