Add an example Android app and a README.md file that details how to compile it.

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+In order to build these examples, add the following two rules to the top-level `WORKSPACE` file (two directories above this file):
+
+```python
+android_sdk_repository(
+    name="androidsdk",
+    path="<path to your Android SDK>",
+    api_level=21,
+    build_tools_version="21.1.1")
+android_ndk_repository(
+    name="androidndk",
+    path="<path to your Android NDK>",
+    api_level=21)
+```
+
+Then the following command can be used to build the example app:
+
+```
+bazel build --android_crosstool_top=@androidndk//:toolchain //examples/android/java/bazel:hello_world
+```
+
+Yes, we know that this is a little clunky. We are working on the following things (and more):
+ * Eliminating the need for the `--android_crosstool_top` command line option
+ * Supporting other architectures than `armeabi-v7a` and compilers other than GCC 4.9
+ * Eliminating the big ugly deprecation message from the console output of Bazel
+
+We also have a nice way to speed up the edit-compile-install development cycle for physical Android devices and emulators: Bazel knows what code changed since the last build, and can use this knowledge to install only the changed code to the device. This currently works with L devices and changes to Java code and Android resources. To try this out, take an `android_binary` rule and:
+ * Set the `proguard_specs` attribute to `[]` (the empty list) or just omit it altogether
+ * Set the `multidex` attribute to `native`
+ * Set the `dex_shards` attribute to a number between 2 and 200. This controls the size of chunks the code is split into. As this number is increased, compilation and installation becomes faster but app startup becomes slower. A good initial guess is 10.
+ * Connect your device over USB to your workstation and enable USB debugging on it
+ * Run `bazel mobile-install --android_crosstool_top=@androidndk//:toolchain <android_binary rule>`
+ * Edit Java code or Android resources
+ * Run `blaze mobile-install --android_crosstool_top=@androidndk//:toolchain --incremental <android_binary rule>`
+
+Note that if you change anything other than Java code or Android resources (C++ code or something on the device), you must omit the `--incremental` command line option. Yes, we know that this is also clunky and we are working on improving it.