SLING-3349 : Guard servlet resolver against no resource type

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1562441 13f79535-47bb-0310-9956-ffa450edef68
SLING-2986 : Fix path handling, especially when the root node is requested

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1562454 13f79535-47bb-0310-9956-ffa450edef68