Small refactoring

[decebals]

I intend to make a refactoring:

• move FileDownloader and SimpleFileDownloader in a new downloader package
• move FileVerifier and VerifierException in verifier package

What you say?

[janhoy]

Or leave the interfaces in the main package, but create sub packages for the implementations?

I don't know how likely it is for the framework to ship with other FileDownloaders to warrant a separate package but who knows? Perhaps more likely to get more UpdateRepositories in the future. In my Solr effort I already have a GitHubUpdateRepository and an ApacheUpdateRepository and they both use the SimpleFileDownloader but some custom Verifiers.

But I don't feel strongly about it, I'm ok with packages for everything, we just need to consider releasing one 2.1.0 version with the move but where the current classes are also present but Deprecated?