[Request] Internal caching repositories

[mirkobrombin]

Is your feature request related to a problem? Please describe. Although Bottles is a program that requires active connection for most of its operations (installing dependencies, components and installers). It is important not to waste GitHub resources (where public repositories are hosted).

Describe the solution you'd like Caching the repositories every X hours and on startup after a Bottles update. This means not only caching the index but also all the manifests in the repositories (very few Kb), so when Bottles has to download something, it will look from the cache first.