MODE-2275 Fixed Schemata caching by the JcrNodeTypeManager, which caused newly registered node types to not be visible as long as they are registered with the same namespace.

One question about our general style, and not so much about this PR. What do you think of the following?

    try {
       return this.repositoryTypeManager.registerNodeType(template, !allowUpdate);
    } finally {
       this.schema = null;
    }

Again, I'm not really suggesting that the PR be changed; it's more of a general question about this kind of pattern. Is it useful? Is it better or worse? If you think it's better, maybe I'll start using it more in the future.