Filter alpha Versions

[mcm1957]

Repobuilder should filter ALPHA Version (version with extensions like 1.2.3-alpha.0 or 1.2.3-rc.9) and only procress normal versions (1.2.3). Standard deploy already refused to set latest label but manual deploy still will insert such versions.

Its OK to deploy alpha versions to npm so users can test them using explicit version specification od tag next (which is set by standard deploy). But such alpha versions should not be published at repository. So repobuilder should use the last known normal version if an alpha is reported from npm. Normally this should be relevant for LATEST repo only.