Move common Prolog predicates to 'gerrit' package

Because user code will need to import our common rules, move them
to a shorter name "gerrit". This is not likely to collide with any
classes in a running server as we will eventually narrow down the
set of classes available to the PrologEnvironment to a smaller set
than the entire running server, and we aren't likely to ever use a
3rd party library from the gerrit.com domain.

Change-Id: I8f111ea2cb58229159d3a72c081a3808cc6c3438

gerrit-server/src/test/java/com/google/gerrit/rules/GerritCommonTest.java

@@ -12,20 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package com.google.gerrit.rules.common;
+package com.google.gerrit.rules;
 
 import com.google.gerrit.common.data.ApprovalType;
 import com.google.gerrit.common.data.ApprovalTypes;
 import com.google.gerrit.reviewdb.ApprovalCategory;
 import com.google.gerrit.reviewdb.ApprovalCategoryValue;
-import com.google.gerrit.rules.PrologTestCase;
 import com.google.inject.AbstractModule;
 
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-public class CommonRulesTest extends PrologTestCase {
+public class GerritCommonTest extends PrologTestCase {
   @Override
   public void setUp() throws Exception {
     super.setUp();
@@ -35,7 +34,7 @@ public class CommonRulesTest extends PrologTestCase {
         verifiedCategory()
     ));
 
-    load("common_rules_test.pl", new AbstractModule() {
+    load("gerrit_common_test.pl", new AbstractModule() {
       @Override
       protected void configure() {
         bind(ApprovalTypes.class).toInstance(types);

gerrit-server/src/test/resources/com/google/gerrit/rules/gerrit_common_test.pl

@@ -12,7 +12,7 @@
 %% See the License for the specific language governing permissions and
 %% limitations under the License.
 
-:- package 'com.google.gerrit.rules.common'.
+:- package 'gerrit'.
 
 
 %% not_same