Include change number in change email footers

Change-Id: Ic0ebc939ef9d2d7d5561602dfda37941a16a3f43

gerrit-server/src/main/java/com/google/gerrit/server/mail/send/ChangeEmail.java

@@ -446,6 +446,7 @@ public abstract class ChangeEmail extends NotificationEmail {
     changeData.put("subject", change.getSubject());
     changeData.put("originalSubject", change.getOriginalSubject());
     changeData.put("ownerEmail", getNameEmailFor(change.getOwner()));
+    changeData.put("changeNumber", Integer.toString(change.getChangeId()));
     soyContext.put("change", changeData);
 
     String subject = change.getSubject();

gerrit-server/src/main/resources/com/google/gerrit/server/mail/ChangeFooter.soy

@@ -47,6 +47,7 @@
 
   Gerrit-MessageType: {$messageClass}{\n}
   Gerrit-Change-Id: {$changeId}{\n}
+  Gerrit-Change-Number: {$change.changeNumber}{\n}
   Gerrit-PatchSet: {$patchSet.patchSetId}{\n}
   Gerrit-Project: {$projectName}{\n}
   Gerrit-Branch: {$branch.shortName}{\n}

gerrit-server/src/main/resources/com/google/gerrit/server/mail/ChangeFooterHtml.soy

@@ -47,6 +47,7 @@
   <p style="{$footerStyle}">
     Gerrit-MessageType: {$messageClass}<br/>
     Gerrit-Change-Id: {$changeId}<br/>
+    Gerrit-Change-Number: {$change.changeNumber}<br/>
     Gerrit-PatchSet: {$patchSet.patchSetId}<br/>
     Gerrit-Project: {$projectName}<br/>
     Gerrit-Branch: {$branch.shortName}<br/>