Making sure file exist before attemping unlinking it. Otherwise cause er...

When "force_unlink true" is use, if the file doesn't already exist, file creation will fail because the old code will attempt to unlink it without checking to see if it exist.

  * file[/etc/resolvconf/resolv.conf.d/tail] action create       [2014-04-27T18:53:31+00:00] INFO: Processing file[/etc/resolvconf/resolv.conf.d/tail] action create (resolvconf::install line 23)

       ================================================================================

       Error executing action `create` on resource 'file[/etc/resolvconf/resolv.conf.d/tail]'
       ================================================================================

       Errno::ENOENT
       -------------
       No such file or directory - /etc/resolvconf/resolv.conf.d/tail

       Resource Declaration:
       ---------------------
       # In /tmp/kitchen/cache/cookbooks/resolvconf/recipes/install.rb

        23: file "/etc/resolvconf/resolv.conf.d/tail" do
        24:   mode    00644
        25:   content "abc"
        26:   action :create
        27:   # Remove file if it is not a regular file (e.g. a symlink)

        28:   # This is useful, as sometimes the backup stored in the file "original"
        29:   # is symlinked to "tail"
        30:   force_unlink true
        31: end

       Compiled Resource:
       ------------------
       # Declared in /tmp/kitchen/cache/cookbooks/resolvconf/recipes/install.rb:23:in `from_file'

       file("/etc/resolvconf/resolv.conf.d/tail") do
         provider Chef::Provider::File

         action [:create]
         retries 0
         retry_delay 2
         guard_interpreter :default
         path "/etc/resolvconf/resolv.conf.d/tail"
         backup 5
         atomic_update true
         force_unlink true
         cookbook_name "resolvconf"
         recipe_name "install"
         mode 420
         content "abc"
       end