SLING-3027 Improve Launchpad Karaf Features

* Downgrade Sling API to 2.22.0
* Add missing capability
diff --git a/src/main/feature/feature.xml b/src/main/feature/feature.xml
index b9b89c1..86a9194 100644
--- a/src/main/feature/feature.xml
+++ b/src/main/feature/feature.xml
@@ -21,7 +21,7 @@
   <!-- Apache Sling -->
   <feature name="sling" version="${project.version}">
     <config external="true" name="org.apache.sling.serviceusermapping.impl.ServiceUserMapperImpl.amended-sling_resourceresolver">mvn:org.apache.sling/org.apache.sling.karaf-configs/${project.version}/config/org.apache.sling.serviceusermapping.impl.ServiceUserMapperImpl.amended-sling_resourceresolver</config>
-    <bundle>mvn:org.apache.sling/org.apache.sling.api/2.23.0</bundle>
+    <bundle>mvn:org.apache.sling/org.apache.sling.api/2.22.0</bundle>
     <bundle>mvn:org.apache.sling/org.apache.sling.auth.core/1.5.0</bundle>
     <bundle>mvn:org.apache.sling/org.apache.sling.engine/2.7.2</bundle>
     <bundle>mvn:org.apache.sling/org.apache.sling.resourceresolver/1.7.0</bundle>
@@ -50,7 +50,8 @@
     <bundle dependency="true">mvn:org.apache.commons/commons-math/2.2</bundle>
     <bundle dependency="true">mvn:org.apache.felix/org.apache.felix.converter/1.0.14</bundle>
     <capability>
-      osgi.service;objectClass=org.apache.sling.engine.SlingRequestProcessor <!-- provided by engine -->
+      osgi.service;objectClass=org.apache.sling.engine.SlingRequestProcessor, <!-- provided by engine -->
+      osgi.service;objectClass=javax.servlet.ServletContext
     </capability>
   </feature>
   <!-- Apache Sling Auth -->