Get CC to work with NFS.

The cloud controller expects NFS to use /var/vcap/nfs/shared and goes
through extra tests to ensure that this directory is writable by user
VCAP.  However, the appbits go to wherever default_fog_connection.local_root specifies.

This change gets the two in alignment.

[#63496220]
Merge pull request #272 from cloudfoundry/cc_nfs_fix

Cc nfs fix