Add a testLean task to exclude extranous tests.

- Exclude swift from travis builds
- Exclude python from travis builds
- Disabling ThrottleTests for leanTest
diff --git a/tests/build.gradle b/tests/build.gradle
index 6c0a7ba..4368ace 100644
--- a/tests/build.gradle
+++ b/tests/build.gradle
@@ -17,7 +17,7 @@
     }
 }
 
-test {
+tasks.withType(Test) {
     systemProperty 'testthreads', System.getProperty('testthreads', '1')
     testLogging {
         events "passed", "skipped", "failed"
@@ -27,6 +27,12 @@
     outputs.upToDateWhen { false } // force tests to run every time
 }
 
+task testLean(type: Test) {
+    exclude '**/*Swift*'
+    exclude '**/*Python*'
+    exclude '**/*ThrottleTests*'
+}
+
 // Add all images needed for local testing here
 test.dependsOn([
     ':core:nodejsAction:distDocker',