Display extension version history

Two user stories, from different perspectives

As a user I want to know what changes have been done to an extension throughout its lifecycle. I want to be able to read a version history entry of a particular version of the extension. I want to be able to read a concatenated version history containing all the version history entries of the extension.

As a publisher I want to describe the changes I’ve done to the extension when publishing a new version of the extension.

Possible technical realization

Add VersionHistory, a dict, with two fields to the metadata-schema

• versionDate: string-typed field 
• versionText: string-typed field 

Validation: is present, versionDate is autogenerated when published, versionText is not empty, 

Add display of version history to the extension details sidebar of the extension mode.