Build: Split distributions into oss and default

This commit makes x-pack a module and adds it to the default
distrubtion. It also creates distributions for zip, tar, deb and rpm
which contain only oss code.

x-pack/qa/build.gradle

@@ -1,3 +1,23 @@
+// this file must exist so that qa projects are found
+// by the elasticsearch x-plugins include mechanism
+
+import org.elasticsearch.gradle.test.RestIntegTestTask
+
+subprojects {
+  // HACK: please fix this
+  // we want to add the rest api specs for xpack to qa tests, but we
+  // need to wait until after the project is evaluated to only apply
+  // to those that rest tests. this used to be done automatically
+  // when xpack was a plugin, but now there is no place with xpack as a module.
+  // instead, we should package these and make them easy to use for rest tests,
+  // but currently, they must be copied into the resources of the test runner.
+  project.tasks.withType(RestIntegTestTask) {
+    File xpackResources = new File(xpackProject('plugin').projectDir, 'src/test/resources')
+    project.copyRestSpec.from(xpackResources) {
+      include 'rest-api-spec/api/**'
+    }
+  }
+}
 
 /* Remove assemble on all qa projects because we don't need to publish
  * artifacts for them. */