Added default unit test from the newer sample projects.

app/src/test/java/com/kabouzeid/gramophone/ExampleUnitTest.java

@@ -0,0 +1,15 @@
+package com.kabouzeid.gramophone;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * To work on unit tests, switch the Test Artifact in the Build Variants view.
+ */
+public class ExampleUnitTest {
+    @Test
+    public void addition_isCorrect() throws Exception {
+        assertEquals(4, 2 + 2);
+    }
+}