The `net-client` project contained more then just the `net-client`.
It contains stuff like `SuppressForbidden` and `Strings` and `IOUtil`
and other things shared between the CLI and JDBC. It also does contain
the http client. Anyway, it makes more sense to call it `shared-client`,
I think.
Alos updated the copywrite dates on the files that I touched because
they are all 2017 files.
Removed some uses of `String.EMPTY` because they don't buy us anything
and require an extra import. `""` is just one less step.
Original commit: elastic/x-pack-elasticsearch@465c6445c4
Nik Everett