Update notes for submitted changes

* BatchRefUpdate: Expand javadocs and add @Nullable
* PackedBatchRefUpdate: Write reflogs
* Extract constants for reflog entry message prefixes

22/e9106224e1514dbee6d6f8271187de606716a6

@@ -0,0 +1,8 @@
+Code-Review+2: Shawn Pearce <spearce@spearce.org>
+Code-Review+1: David Pursehouse <david.pursehouse@gmail.com>
+Verified+1: Hudson CI
+Submitted-by: David Pursehouse <david.pursehouse@gmail.com>
+Submitted-at: Fri, 28 Jul 2017 05:40:45 -0400
+Reviewed-on: https://git.eclipse.org/r/101457
+Project: jgit/jgit
+Branch: refs/heads/master

a1/e11461cc2d2c83c4898bde7ad885baaecd0b14

@@ -0,0 +1,9 @@
+Code-Review+2: David Pursehouse <david.pursehouse@gmail.com>
+Code-Review+2: Shawn Pearce <spearce@spearce.org>
+Verified+1: Hudson CI
+Code-Review+2: Jonathan Nieder <jrn@google.com>
+Submitted-by: David Pursehouse <david.pursehouse@gmail.com>
+Submitted-at: Fri, 28 Jul 2017 05:40:45 -0400
+Reviewed-on: https://git.eclipse.org/r/101583
+Project: jgit/jgit
+Branch: refs/heads/master

db/b137e0f3ccaef7db4982127da1c7bdfc581e98

@@ -0,0 +1,9 @@
+Code-Review+2: Shawn Pearce <spearce@spearce.org>
+Code-Review+2: Jonathan Nieder <jrn@google.com>
+Code-Review+2: David Pursehouse <david.pursehouse@gmail.com>
+Verified+1: Hudson CI
+Submitted-by: David Pursehouse <david.pursehouse@gmail.com>
+Submitted-at: Fri, 28 Jul 2017 05:40:45 -0400
+Reviewed-on: https://git.eclipse.org/r/101456
+Project: jgit/jgit
+Branch: refs/heads/master