- apply changes to test suite for new parameters in  OAuth::Client and AccessToken
 - update access_token['id_token'] to access_token.token in strategies/google_oauth2.rb
 - alter access_token.token.nil? to nil_or_empty() due to aforementioned changes

 - alter test "...when the access token is empty or nil"
 - v2.0.6 fixed regression in v2.0.5 so test client is now initialized with refresh_token

 - update test "...when the access token is empty or nil"
 - remove redundant "let(:client) do" declaration

 - allow OAuth::Client initializations to raise error flags

 - convert unnecessary "let(:client) do" to instance variable