libs: switch to jpnfs-0.6.1

Changelog for jpnfs-0.5.8..nfs4j-0.6.1
    * [3e3532d] src: rename package org.dcache.chimera.nfs to org.dcache.nfs
    * [f8ec52f] nfs: ExportFile returns Iterable instead of Collection
    * [3825d6a] pom: java7 is allowed
    * [c1f4711] src: towards java7: use diamond operator
    * [3b68d7f] src: towards java7: use try-with-resources
    * [4aa0cd0] src: towards java7: use muticatch
    * [2e90166] nfsv4: bitmap should implement Iterable interface
    * [db9f154] nfsv4: consult export file on getRootInode()
    * [e40f159] change version number schema to M.m.p
    * [38c61df] test: add unit test for FileHandle and FileHandleBuilder
    * [c79fa4d] vfs: construct new file handles from old one
    * [9b08969] vfs: support old file handles
    * [483f7c7] client: add lookup by fh
    * [bae75e1] pom: scm should point to dCache's github repository
    * [5b448bc] nfsv41: propagate layout return errors on close
    * [9cf5505] nfsv41: consult backend 'filesystem' for read/write access
    * [7969395] nfsv41: rename NFS4Client#sessionsEmpty() to NFS4Client#hasSessions().
    * [86e9cad] nfs: added support for sec flavor in export file
    * [c928dae] vfs: check security flavor used by client
    * [30ee45f] nfs: ignore and log export entries with unsupported options
    * [bb7d28f] nfsv3: reply correct auth flavor of mount
    * [2610307] junit: refactor v4 test to reduce code duplication
    * [302c210] nfsv41: fix open stateid leak
    * [f9d6c2c] nfsv41: garbage-collect expired sessions
    * [3e76f8e] nfs: FsExport takes  builder in the constructor
    * [fd2848f] exports: added support for all_squash option
    * [a09c9c9] pseudofs: respect all_squash option
    * [6bcdd84] exports: fix broken commit
    * [623c675] exports: added support fot anonuid/anongid
    * [5510940] exports: improve toString()
    * [ea6ec12] pom: update slf4j and logback libraries
    * [2fb54ef] logging: update to use varargs
    * [f1bc992] nfs: fix readdir caching
    * [a61bdf3] nfsv: fix operation position check
    * [48011ed] pom: switch to oncrpc4j-2.1.0
    * [95443ce] utils: make guava Cache JMX aware
    * [ecf6a9f] utils: fix leftovers from jul to slf4j migration
    * [f7fdc97] src: reorganise project into multi module maven project
    * [a51eb1a] core: limit number of states owned by cliet
    * [60dc0f3] nfs: use Cache#get to populate READDIR cache
    * [2e6e17c] vfs: use inodeToBytes to generate file handle for chimera
    * [03357e6] vfs: update API interface to match new changes in chimera

update corresponding code

Acked-by: Paul Millar
Target: master
Require-book: no
Require-notes: no