Add govuk_app_config version to every sentry call

This is to simplify debugging problems with error handling, see:
https://trello.com/c/guK81BGF/2239-3-send-govukappconfig-version-with-errors

lib/govuk_app_config/govuk_error.rb

@@ -1,6 +1,7 @@
 require "sentry-raven"
 require "govuk_app_config/govuk_statsd"
 require "govuk_app_config/govuk_error/configuration"
+require "govuk_app_config/version"
 
 module GovukError
   def self.notify(exception_or_message, args = {})
@@ -9,6 +10,9 @@ def self.notify(exception_or_message, args = {})
     args[:extra] ||= {}
     args[:extra].merge!(parameters: args.delete(:parameters))
 
+    args[:tags] ||= {}
+    args[:tags][:govuk_app_config_version] = GovukAppConfig::VERSION
+
     Raven.capture_exception(exception_or_message, args)
   end
 

lib/govuk_app_config/version.rb

@@ -1,3 +1,3 @@
 module GovukAppConfig
-  VERSION = "2.7.1".freeze
+  VERSION = "2.8.0".freeze
 end

spec/lib/govuk_error_spec.rb

@@ -16,7 +16,15 @@
 
       GovukError.notify(StandardError.new, parameters: "Something")
 
-      expect(Raven).to have_received(:capture_exception).with(StandardError.new, extra: { parameters: "Something" })
+      expect(Raven).to have_received(:capture_exception).with(StandardError.new, hash_including(extra: { parameters: "Something" }))
+    end
+
+    it "sends the version along with the request" do
+      allow(Raven).to receive(:capture_exception)
+
+      GovukError.notify(StandardError.new, parameters: "Something")
+
+      expect(Raven).to have_received(:capture_exception).with(StandardError.new, hash_including(tags: { govuk_app_config_version: /^[0-9.]+$/ }))
     end
   end