Encode Exec runtime manifests in deployment configuration.

Add manifest schema.
Add utilities to read Exec runtimes from manifest.
Add runtimes manifest to ansible group vars.
Write out manifest to whisk.properties and make available through WhiskConfig.

tests/src/whisk/core/entity/test/ExecManifestTests.scala

+/*
+ * Copyright 2015-2016 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package whisk.core.entity.test
+
+import org.junit.runner.RunWith
+import org.scalatest.FlatSpec
+import org.scalatest.Matchers
+import org.scalatest.junit.JUnitRunner
+
+import spray.json._
+import spray.json.DefaultJsonProtocol._
+import whisk.core.entity.ExecManifest
+import whisk.core.entity.ExecManifest._
+
+@RunWith(classOf[JUnitRunner])
+class ExecManifestTests
+    extends FlatSpec
+    with Matchers {
+
+    behavior of "ExecManifest"
+
+    it should "read a valid configuration" in {
+        val k1 = RuntimeManifest("k1")
+        val k2 = RuntimeManifest("k2", default = Some(true))
+        val p1 = RuntimeManifest("p1")
+        val mf = JsObject("k" -> Set(k1, k2).toJson, "p1" -> Set(p1).toJson)
+        val runtimes = ExecManifest.runtimes(mf).get
+
+        Seq("k1", "k2", "p1").foreach {
+            runtimes.knownContainerRuntimes.contains(_) shouldBe true
+        }
+
+        runtimes.knownContainerRuntimes.contains("k3") shouldBe false
+
+        runtimes.resolveDefaultRuntime("k1") shouldBe Some(k1)
+        runtimes.resolveDefaultRuntime("k2") shouldBe Some(k2)
+        runtimes.resolveDefaultRuntime("p1") shouldBe Some(p1)
+
+        runtimes.resolveDefaultRuntime("k:default") shouldBe Some(k2)
+        runtimes.resolveDefaultRuntime("p1:default") shouldBe None
+    }
+
+}