Canvas.revision

and display the revision on /plugins

test plan: without a VERSION file, visit /plugins and see the "Unknown"
displayed. With a VERSION file, visit /plugins and see the first line of
that file displayed.

Change-Id: I0bcb3c855c70ba444158e17302eadab317dffb02
Reviewed-on: https://gerrit.instructure.com/9197
Reviewed-by: Brian Palmer <brianp@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Hudson <hudson@instructure.com>

Author: codekitchen

app/views/plugins/index.html.erb

@@ -5,6 +5,12 @@
   jammit_css 'plugins'
 %>
 
+<h2><%= t :instructure_canvas, "Instructure Canvas" %></h2>
+
+<p>
+  Revision: <%= Canvas.revision || t(:canvas_revision_unknown, "Unknown") %>
+</p>
+
 <h2><%= t :page_title, "Canvas Plugins" %></h2>
 
 <% if @plugins.any? %>

lib/canvas.rb

@@ -126,4 +126,12 @@ def self.reloadable_plugin(dirname)
       p[0, base_path.length] == base_path
     }
   end
+
+  def self.revision
+    return @revision unless @revision.nil?
+    if File.file?(Rails.root+"VERSION")
+      @revision = File.readlines(Rails.root+"VERSION").first.try(:strip)
+    end
+    @revision ||= false
+  end
 end