Follow upstream's renaming of method to get current user

In gerrit's

  85f0487714e005b478eee5b28efab22bf5b7a5e2

commit, the getCurrentUser accessor got renamed to getUser. We follow
this move to allow compilation against gerrit master.

Bug: Issue 3618
Change-Id: I992761e5fd9fa48c82809590499eaca75a6071ae
diff --git a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserResolver.java b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserResolver.java
index fea4548..9a4a81f 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserResolver.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/serviceuser/ServiceUserResolver.java
@@ -100,7 +100,7 @@
     try {
       RequestContext context = new RequestContext() {
         @Override
-        public CurrentUser getCurrentUser() {
+        public CurrentUser getUser() {
           return new CurrentUser(null) {
 
             @Override