Build: Remove x-pack client jar

The x-pack client jar and api jar are exactly the same: the entirety of
x-pack. Since we added the x-pack-transport jar, we no longer really
want the client jar as it is confusing. Additionally, it causes jar hell
when a test for an extension uses the transport client. This change
removes the client jar, and makes the x-pack transport client use the
api jar instead. This sounds odd at first, but since transport client is
going away eventually, it is a stopgap, and works.

closes elastic/elasticsearch#3309

Original commit: elastic/x-pack-elasticsearch@ee7a2c12c0

elasticsearch/build.gradle

@@ -14,5 +14,5 @@ subprojects {
     approvedLicenses = ['Elasticsearch Confidential']
     additionalLicense 'ESCON', 'Elasticsearch Confidential', 'ELASTICSEARCH CONFIDENTIAL'
   }
-  ext.projectSubstitutions += [ "org.elasticsearch.plugin:x-pack-client:${version}": ':x-plugins:elasticsearch:x-pack' ]
+  ext.projectSubstitutions += [ "org.elasticsearch.plugin:x-pack-api:${version}": ':x-plugins:elasticsearch:x-pack' ]
 }

elasticsearch/x-pack-transport/build.gradle

@@ -7,7 +7,9 @@ apply plugin: 'nebula.maven-scm'
 group = 'org.elasticsearch.client'
 
 dependencies {
-    compile "org.elasticsearch.plugin:x-pack-client:${version}"
+    // this "api" dependency looks weird, but it is correct, as it contains
+    // all of x-pack for now, and transport client will be going away in the future. 
+    compile "org.elasticsearch.plugin:x-pack-api:${version}"
     compile "org.elasticsearch.client:transport:${version}"
     testCompile "com.carrotsearch.randomizedtesting:randomizedtesting-runner:${versions.randomizedrunner}"
     testCompile "junit:junit:${versions.junit}"

elasticsearch/x-pack/build.gradle

@@ -12,7 +12,6 @@ esplugin {
   name 'x-pack'
   description 'Elasticsearch Expanded Pack Plugin'
   classname 'org.elasticsearch.xpack.XPackPlugin'
-  hasClientJar = true
 }
 
 ext.versions = [