changed ApiError to NonSuccessError for non success impersonate

lib/castle/client.rb

@@ -82,7 +82,7 @@ def impersonate(options = {})
       add_timestamp_if_necessary(options)
       command = Castle::Commands::Impersonate.new(@context).build(options)
       @api.request(command).tap do |response|
-        raise Castle::ApiError, 'Impersonate request failed' unless response[:success]
+        raise Castle::NonSuccessError, 'Impersonate request failed' unless response[:success]
       end
     end
 

lib/castle/errors.rb

@@ -26,4 +26,6 @@ class InvalidParametersError < Castle::ApiError; end
   class UnauthorizedError < Castle::ApiError; end
   # all internal server errors
   class InternalServerError < Castle::ApiError; end
+  # non success response
+  class NonSuccessError < Castle::ApiError; end
 end

spec/lib/castle/client_spec.rb

@@ -97,7 +97,7 @@
       let(:response_body) { {}.to_json }
 
       it do
-        expect { client.impersonate(options) }.to raise_error(Castle::ApiError)
+        expect { client.impersonate(options) }.to raise_error(Castle::NonSuccessError)
       end
     end
   end