Fix possible NPE in ConvertToContentPackageAction

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1630601 13f79535-47bb-0310-9956-ffa450edef68
SLING-3573 - Local resources which are no longer present in the
repository are not deleted when importing

When importing, remove files not touched by the import action and which
fall in the scope of synchronization.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1630602 13f79535-47bb-0310-9956-ffa450edef68
SLING-4023 - Files with a colon in their names are imported with an
incorrect name

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1630603 13f79535-47bb-0310-9956-ffa450edef68
Prevent spurious node reordering when resources were not actually
changed

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1630604 13f79535-47bb-0310-9956-ffa450edef68