Implement empty postRun() InitStep

Add an empty postRun() method for satisfying the
new InitStep interface in Gerrit 2.9-SNAPSHOT.
GitBlit does not require any action to be performed
after the init, so the method is empty.

Change-Id: I4d59b34e8a205a5fa2ed8f2ec1490b0d9e6a3c42

src/main/java/com/googlesource/gerrit/plugins/gitblit/GitBlitInitStep.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/gitblit/GitBlitInitStep.java b/src/main/java/com/googlesource/gerrit/plugins/gitblit/GitBlitInitStep.java
index d76594b..345a70a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/gitblit/GitBlitInitStep.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/gitblit/GitBlitInitStep.java
@@ -54,4 +54,7 @@
     gitWeb.string("Link name", "linkname", "GitBlit");
   }
 
+  @Override
+  public void postRun() throws Exception {
+  }
 }