Added Android app source code (#94)

* Added android app

* Added Google Play picture

* Update rc.md

* Update rc.md

* Update rc.md

* Update rc.md

* Update rc.md

* Update rc.md

* Create android.md

* Update SUMMARY.md

* Update android.md

* Update android.md

apps/android/app/src/test/java/express/copter/cleverrc/ExampleUnitTest.kt

@@ -0,0 +1,17 @@
+package express.copter.cleverrc
+
+import org.junit.Test
+
+import org.junit.Assert.*
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}