Move HDFS-8337 to branch 2.8 in CHANGES.txt.

(cherry picked from commit 20c03c96066752f0a7158846de4d7bc4253e83f6)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -593,6 +593,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8615. Correct HTTP method in WebHDFS document.
     (Brahma Reddy Battula via aajisaka)
 
+    HDFS-8337. Accessing httpfs via webhdfs doesn't work from a jar with
+    kerberos. (Yongjun Zhang)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
@@ -730,9 +733,6 @@ Release 2.7.1 - UNRELEASED
     HDFS-8626. Reserved RBW space is not released if creation of RBW File
     fails. (kanaka kumar avvaru via Arpit Agarwal)
 
-    HDFS-8337. Accessing httpfs via webhdfs doesn't work from a jar with
-    kerberos. (Yongjun Zhang)
-
 Release 2.7.0 - 2015-04-20
 
   INCOMPATIBLE CHANGES