Add :data_bag_keyfile attribute to the LWRP.

If :data_bag_keyfile is specified in the resource, it will point to
an alternate filename in which the encryption key associated with the
encrypted databag is stored. If it is not specified, the Chef default
behavior of attempting to use Chef::Config[:encrypted_data_bag_secret]
or then "/etc/chef/encrypted_data_bag_secret"
Merge branch 'higanworks-cookbooks-manage_by_attr' into testing
allow specification of data bag secret

  - new attribute added: data_bag_secret
  - defaults to /etc/chef/encrypted_data_bag_secret
Merge branch 'kechagia-data_bag_secret' into testing

Conflicts:
	README.md
	providers/manage.rb
	resources/manage.rb
certificate v0.2.0

Cleaning up the backlog of PRs

* @kechagia added data_bag_secret attribute
* @sawanoboly added smartos paths, and recipe `certificate::manage_by_attributes`
Certificate v0.2.1

* Fixes issue #11, reported by @tmatilia