Add missing bundle install

Author: tillsc

integration/runnable_w_bundler_test/pom.xml

@@ -47,6 +47,10 @@
         <groupId>org.jruby.maven</groupId>
         <artifactId>jruby-maven-plugin</artifactId>
         <executions>
+          <execution>
+            <id>bundle-install</id>
+            <phase>initialize</phase>
+          </execution>
           <execution>
             <id>warble</id>
             <phase>pre-integration-test</phase>