As a pipe2 developer I want my semantic versions to be enforced upon registring

[abbec]

Acceptance Criteria

• Any potentially breaking change forces and update to major version.
  • Deleting an input or output
  • changing and input or output type (if they can’t be connected any more)
  • changing execution environment

Other changes should result in either a minor version or a patch version

• if checksum of the code is equal and tags are equal (and everything else is equal) reject it?

[sakarias88]

We must add another criteria to not allow arbitrarily bumping version.

Example:
Imagine we have function with version 1.0.0.
User wants to publish 1.2.0.
This request must be denied since 1.1.0 does not exist yet.