Miscellaneous small documentation fixes.

Most of these I noticed on my own. The change to docs/html/tools/testing/testing_ui.jd is mentioned in a bug report:
https://code.google.com/p/android/issues/detail?id=56324

Signed-off-by: Mark Doliner <markdoliner@google.com>
diff --git a/core/java/android/content/Loader.java b/core/java/android/content/Loader.java
index 911e49c..a045b3a 100644
--- a/core/java/android/content/Loader.java
+++ b/core/java/android/content/Loader.java
@@ -24,7 +24,7 @@
 import java.io.PrintWriter;
 
 /**
- * An abstract class that performs asynchronous loading of data. While Loaders are active
+ * A class that performs asynchronous loading of data. While Loaders are active
  * they should monitor the source of their data and deliver new results when the contents
  * change.  See {@link android.app.LoaderManager} for more detail.
  *