maven_install is strongly superior to previous forms of grabbing dependencies
from Maven as it computes the appropriate versions to use from the full
transitive dependencies of all libraries used by an application. It also has
much less boilerplate and includes dependencies with generated targets.
In the future we will drop the jvm_maven_import_external usages and require
maven_install, at which point we can swap to using the `@maven' repository and
no longer depend on compat_repositories.
Fixes#5359
## Bazel
If you prefer to use Bazel:
```
(With Bazel v0.4.5 or above.)
$ bazel build :hello-world-server :hello-world-client
$ # Run the server:
$ bazel-bin/hello-world-server
$ # In another terminal run the client
$ bazel-bin/hello-world-client
```