Multiplatform test annotations

Actual annotations are provided in kotlin-test-junit on JVM side
and in kotlin-test-js on JS side.

#KT-19696

libraries/kotlin.test/annotations-common/src/main/kotlin/kotlin.test/Annotations.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2010-2017 JetBrains s.r.o.
+ *
+ * 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 kotlin.test
+
+/**
+ * Marks a function as a test.
+ */
+public expect annotation class Test()
+
+/**
+ * Marks a test or a suite as ignored.
+ */
+public expect annotation class Ignore()
+
+/**
+ * Marks a function to be invoked before each test.
+ */
+public expect annotation class BeforeTest()
+
+/**
+ * Marks a function to be invoked after each test.
+ */
+public expect annotation class AfterTest()