Add version file and meta generator tag (#1807)

* Add version file and meta generator tag

It's hard to know which version of the code you're looking at.
If we can keep this up-to-date in our release management then we'll be
able to tell which version we see deployed by checking the page source.

* rubocop

CHANGELOG.md

@@ -6,6 +6,9 @@ and releases in Discovery project adheres to [Semantic Versioning](http://semver
 
 ## [Unreleased]
 
+### Added
+- Add version file and meta generator tag [#1343](https://github.com/ualbertalib/discovery/issues/1343)
+
 ### Changed
 - for Docker add bundler build config to make sassc gem portable [#1796](https://github.com/ualbertalib/discovery/issues/1796)
 

app/views/layouts/application.html.erb

@@ -15,6 +15,7 @@
 
     <title>University of Alberta Libraries</title>
     <%= opensearch_description_tag application_name, opensearch_catalog_url(format: 'xml') %>
+    <meta name="generator" content="<%= "Discovery #{Discovery::VERSION} - https://github.com/ualbertalib/discovery" %>">
     <%# favicon_link_tag asset_path('favicon.ico') %>
     <%= favicon_link_tag 'favicon.ico' %>
     <%= stylesheet_link_tag 'application', 'https://fonts.googleapis.com/css?family=Open+Sans:400,700,400italic|Abel', media: 'all' %>

config/application.rb

@@ -8,6 +8,8 @@
 Bundler.require(*Rails.groups)
 
 module Discovery
+  VERSION = '3.0.11'.freeze # used in application layout meta generator tag
+
   class Application < Rails::Application
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration should go into files in config/initializers