Add an extension to the FsCache tests which verifies cache coherency and
atomicity of the FsCache implementation. Additionally, if available, it
utilizes a cache on NFS storage to test network-support.
Unfortunately, the stress-tests keep triggering kernel-oopses in the NFS
client driver, so they are disabled for now. However, once investigated,
we can re-enable them.
Signed-off-by: David Rheinsberg <david.rheinsberg@gmail.com>
