Android modifications to existing files from OkHttp / okio

This CL contains all changes to existing files that were previously
introduced by AOSP commit 36132b3cd2c814e057c775adc821ae0fb12aeb4c

In addition, this CL adds assertNotEquals() to RealWebSocketTest.java
to make it run on AOSP's version of JUnit.

This commit reverts all of the changes to okio from the previous CL
*except* for slight tweaks to README.android.

Change-Id: Ia6c8c3ae33573f8bb3bfd638376f1421286472b2
diff --git a/README.android b/README.android
index c450e1e..3ad84fc 100644
--- a/README.android
+++ b/README.android
@@ -15,5 +15,11 @@
     okhttp/src/main/java-templates/com/squareup/okhttp/internal/Version.java
     for Android.
 
+All source changes (besides imports) marked with ANDROID-BEGIN and ANDROID-END:
+  - Commenting of code that references APIs not present on Android.
+  - @Ignore or comment out tests for functionality not supported on Android.
+  - Work around JUnit 4.11 not being available on Android by adding a
+    assertNotEquals() method to affect tests.
+
 okio/ contains a snapshot of the Okio project. See okio/README.android for
 details.