NFSv3 functional testing via pynfs

[chucklever]

Capturing a wacky idea that has been floating around for some time: we'd like to add NFSv3 testing to pynfs. There are some NFSv3-specific areas that need the kind of detailed functional testing that pynfs does. Examples include:

• Guarded and exclusive SETATTR operations
• The behavior of pre-op and post-op attributes
• NLM operations