Add more package metadata

[beforan]

The following package metadata should be easily added to the csproj, bringing this package in line with FeedbackMessage:

• [x] PackageLicenseUrl
• [x] PackageProjectUrl
• [x] RepositoryUrl

[beforan]

Also PackageId can be removed; NuGet defaults to the csproj name as package id if one isn't specified.

It's less data to maintain if the default suits us.

• [x] remove PackageId

[beforan]

16 fixesthis