Add snapshot functionality to Herd.

[MikhailMalyutin]

Currently Herd can be used only for releases. But in enterprise development, then several persons works on the same big project, it is absolutely necessary to have SNAPSHOT functionality. If module version have SNAPSHOT postfix, such modules must not be cached. And must be possible to upload artifacts on each CI build with same SNAPSHOT version.

Without this functionality developers have to write some own workarounds to emulate SNAPSHOT functionality. For example build snapshot artifacts on CI server to shared between all developers NFS folder. But this is only workaround, there must be official standard way to support SNAPSHOT functionality.

[jvasileff]

I agree this is critically important.

If module version have SNAPSHOT postfix, such modules must not be cached

Some caching is needed to support offline work and to avoid hitting the server for every compile. Something configurable would be nice. Gradle defaults to 24hrs for "changing modules". See https://docs.gradle.org/4.0.1/userguide/dependency_management.html#sec:controlling_caching

[FroMage]

Sure, that all sounds fine and I can help anyone who wants to contribute this feature, but frankly I won't have the time for this soon.