This ticket is a first step of the work needed for WT-1228. There are three goals for this ticket:

• demonstrate caching for "file:" uri (i.e. close, open, close, open, etc. of the same "file:" uri should reuse the same cursor).
• demonstrate caching for simple "table:" uri (same test but with "table:" that has no column groups or indices) (i.e. MongoDB use case)
• demonstrate caching for complex "table:" uri

In order to verify that caching is taking place, we probably need some basic statistics in place. That way we'll be able to write some python tests.