Added cookbook directive to the template section to allow using the LWRP from another cookbook

When using the LWRP directly from my own cookbook it fails as it cannot find the template. According to the following discussion - https://tickets.opscode.com/browse/CHEF-1490 template inheritance is not supported in chef and we need explicitly to tell the template provider which cookbook to search for the template.
I have verified locally that this solution works by adding ```cookbook    'user'``` to ```providers/account.rb``` as follows:
```
  resource = template "#{@home}/.ssh/authorized_keys" do
    owner       l_username
    group       l_primary_group
    mode        '0600'
    variables   :ssh_keys => l_ssh_keys
    source      'authorized_keys.erb'
    cookbook    'user'
  end
```