Filesystem Repo doesn't list modules in descending order of versions

[isc-shuliu]

%IPM.Repo.Filesystem.PackageService:ListModules() doesn't return the latest version of each module by default, which is different from %IPM.Repo.Remote.PackageService:ListModules().

This affects #582 and ongoing work of #586

We should enforce a protocol such that any subclass of %IPM.Repo.IPackageService implements the ListModules() method in a manner that returns the latest version first.

[isc-shuliu]

After a closer look, the problem is %IPM.Repo.Filesystem.PackageService:ListModules() returns each module-version pair as an individual row instead of aggregating all versions of module to a single row (as required by the ROWSPEC of %IPM.Utils.Module:GetModuleList)