SLING-7084 - Coverage report is not generated correctly for HTL modules

* switched to slingstart-maven-plugin 1.7.7-SNAPSHOT, until 1.7.8 is released
* updated JaCoCo version to 0.7.9
* based tests on released Apache Sling Launchpad 9
* increased LaunchpadReadyIT timeouts from 20 to 60 seconds

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1806038 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 1ec9605..bb1f19f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -51,7 +51,7 @@
 
     <properties>
         <antlr.version>4.1</antlr.version>
-        <jacoco.maven.plugin.version>0.7.6.201602180812</jacoco.maven.plugin.version>
+        <jacoco.maven.plugin.version>0.7.9</jacoco.maven.plugin.version>
     </properties>
 
     <!-- ======================================================================= -->