Omit spec version, add licenses

[HebaruSan]

Motivation

As of KSP-CKAN/CKAN#4155, spec_version is optional in netkans, so it doesn't need to be included in pull requests anymore.

KSP-CKAN/NetKAN-Infra#336 removed it for the SpaceDock webhook, but it's still generated by the metadata webtool.

Changes

• Now the generated metadata no longer includes spec_version.
• Now the list of licenses is updated to include everything allowed by the schema
• Some visual problems with the license field are cleaned up
• Mod version is moved to the end of its section because it should almost never be filled out by users