Provide client/server JAR in releases

[olivierlemasle]

Release 0.1.6 of jsonnet provided the client/server version of sjsonnet.

However, subsequent releases (from 0.1.7 to 0.2.2) do not contain sjsonnet.client.SjsonnetClientMain.

This change was not documented (neither in the changelog nor in GitHub releases), and do depend on a commit so there's no trace of it.

It would be great if you could provide both versions (jvm and server) as GitHub releases. If you don't want to, please consider adding a note in changelog to explain the change.