SLING-2989 - [Tooling] integrate with vlt once available

Moved the ImportRepositoryContentAction into its own separate class, for
reusability.

git-svn-id: https://svn.apache.org/repos/asf/sling/branches/tooling-ide-vlt@1522918 13f79535-47bb-0310-9956-ffa450edef68
ProjectHelper - gracefully handled deleted projects being deployed.

git-svn-id: https://svn.apache.org/repos/asf/sling/branches/tooling-ide-vlt@1522919 13f79535-47bb-0310-9956-ffa450edef68
SLING-2989 - [Tooling] integrate with vlt once available

Make the SerializationKindManager part of the api bundle and make the
SerializationManager stateful.

git-svn-id: https://svn.apache.org/repos/asf/sling/branches/tooling-ide-vlt@1522920 13f79535-47bb-0310-9956-ffa450edef68