Bugs in Data Bag Item Resource / Object

On Ridley:master.

`conn.data_bag.find("my_data_bag").item.find("my_item").decrypt`

* Undefined method 'data_bag_secret'

~~After 4559e983472fb88e524c3ee6f364f63841199fdd, decrypt works, but decypt_value does not for some reason.~~

~~`conn.data_bag.find("my_data_bag").item.find("my_item").decrypt_value("foo")`~~
* ~~OpenSSL::Cipher::CipherError: wrong final block length~~

nevermind, I was using the `decrypt_value` API incorrectly. Will add docs.