Convert 3 email classes to file based templates.

Convert the NewChange, RegisterNewEmail and ReplacePatchSet
classes to use file based velocity templates which an admin
may edit.  Factor out getChangeDetail and getReviewersNames
from formatChangeDetail and formatSalutation respectively
to enable this.

Change-Id: I36aa7051f06c7641114e2e681639267769846c22

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

@@ -243,6 +243,7 @@ public abstract class ChangeEmail extends OutgoingEmail {
     return detail.toString();
   }
 
+
   /** Get the patch list corresponding to this patch set. */
   protected PatchList getPatchList() {
     if (patchSet != null) {