Move master onto gerrit-3.12

Consume most recent 3.12-rc4 plugin API.
Bump version forward.
Created stable-3.11 for stable release work.

Change-Id: I8e71fc715650ec1dca69ccf704c5d32ed376794c

pom.xml

diff --git a/pom.xml b/pom.xml
index 373052b..d0f5ec7 100644
--- a/pom.xml
+++ b/pom.xml
@@ -7,10 +7,10 @@
     <groupId>com.googlesource.gerrit.plugins</groupId>
     <artifactId>ai-code-review</artifactId>
     <packaging>jar</packaging>
-    <version>3.11.0</version>
+    <version>3.12.0</version>
     <properties>
         <Gerrit-ApiType>plugin</Gerrit-ApiType>
-        <Gerrit-ApiVersion>3.11.0-rc1</Gerrit-ApiVersion>
+        <Gerrit-ApiVersion>3.12.0-rc4</Gerrit-ApiVersion>
         <maven.test.skip>false</maven.test.skip>
     </properties>
     <build>