Add ability to specify buffer sizes

[boris-petrov]

Fixes https://issues.apache.org/jira/projects/VFS/issues/VFS-705.

[garydgregory]

See comments in individual farms.
The new public methods are missing unit tests.

[boris-petrov]

I'm not sure what kind of tests to write. This is pretty much not adding any new functionality, just exposing an API that Java already has. Any ideas?

[garydgregory]

I'm not sure what kind of tests to write. This is pretty much not adding any new functionality, just exposing an API that Java already has. Any ideas?

Suggestions for tests:

• Validate input:
  -- What happens when I pass in a negative number?
  -- What happens when I pass in 0?
• Do I really get a buffer sized N? IOW, is the parameter used at all?

[boris-petrov]

OK, I pushed a couple of tests. They depend on the fact that the BufferedInput/OutputStream constructors check the size argument and throw an exception if it is <= 0. Unfortunately I can't check the buffer size as it is a protected variable in the class (unless we expose it in the MonitorInput/OutputStream classes which would be ugly).

[boris-petrov]

Javadoc comments fixed.