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

[iroller]

• 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

[avleen]

This merge has left the master branch in a broken state.

When trying to add users, the user resource seems to not create the account. usermod never runs.

Eg, on Ubuntu 12.04:

Recipe: users::sysadmins
  * users_manage[sysadmin] action create[2014-03-11T19:47:31-07:00] FATAL: Cannot determine filesystem type for "/home/avleen"
Recipe: <Dynamically Defined Resource>
  * ruby_block[bailing-out] action create

Because the account isn't created, running stat against a non-existant directory fails.

[sethvargo]

@avleen don't work off master... That's why we have releases on the community site.

[iroller]

This should fix the problem: https://github.com/sethvargo-cookbooks/users/pull/48