Test clusters currently has its own set of logic for dealing with
finding different versions of Elasticsearch, downloading them, and
extracting them. This commit converts testclusters to use the
DistributionDownloadPlugin.
This reworks how we configure the `shadow` plugin in the build. The major
change is that we no longer bundle dependencies in the `compile` configuration,
instead we bundle dependencies in the new `bundle` configuration. This feels
more right because it is a little more "opt in" rather than "opt out" and the
name of the `bundle` configuration is a little more obvious.
As an neat side effect of this, the `runtimeElements` configuration used when
one project depends on another now contains exactly the dependencies needed
to run the project so you no longer need to reference projects that use the
shadow plugin like this:
```
testCompile project(path: ':client:rest-high-level', configuration: 'shadow')
```
You can instead use the much more normal:
```
testCompile "org.elasticsearch.client:elasticsearch-rest-high-level-client:${version}"
```
This commit moves the ML QA tests to be a sub-project of ML. The purpose
of this refactoring is to enable ML developers to run
:x-pack:plugin:ml:check and run the vast majority of a ML tests with a
single command (this still does not contain the ML REST tests, nor the
upgrade tests). This simplifies local development for faster iteration.
Ryan Ernst
Alpar Torok
Mark Vieira
Gordon Brown
Nik Everett
Jason Tedor