Latest OpenLibrary API changes breaks gem

[cenotaph]

Doing any lookup by OLID throws:

KeyError: key not found: :ciphers

[garethfr]

think this is a problem with the version of rest-client

Installing rest-client version 2.1.0 fixes this for me. I'm making a PR for this change now

[garethfr]

this PR fixes the :ciphers issue
#35