[COOK-4404] Determine file system and allow not managing NFS home directories

* add 'manage_nfs_home_dirs' attribute for manage resource
* determine FS type before managing it
* manage all FS types by default to keep previous behaviour
* add tests

Keeping default behaviour by managing all home dirs by default not to break anything.
Not fully covered with tests since I was unable to find a way of stubbing `` or system() output with chefspec.

Please note that it should be merged only after my previous pull request since it uses testing environment configured by it:
https://github.com/opscode-cookbooks/users/pull/40