Add --install-all-plugins (from gerrit.war) option to pgm init

Automatically installs all plugins from gerrit.war without asking. This
option cannot be supplied alongside --install-plugin. If it is, there is
a message about this to the user and the init command aborts.

Change-Id: Ia793e64d2cb24b34ffd7f6c33677701c8b6d43d4

gerrit-pgm/src/test/java/com/google/gerrit/pgm/init/UpgradeFrom2_0_xTest.java

@@ -71,8 +71,8 @@ public class UpgradeFrom2_0_xTest extends InitTestCase {
     old.save();
 
     final InMemorySecureStore secureStore = new InMemorySecureStore();
-    final InitFlags flags =
-        new InitFlags(site, secureStore, Collections.<String> emptyList());
+    final InitFlags flags = new InitFlags(site, secureStore,
+        Collections.<String> emptyList(), false);
     final ConsoleUI ui = createStrictMock(ConsoleUI.class);
     Section.Factory sections = new Section.Factory() {
       @Override