allow configuring some dj worker options in the yml

It'd be nice to have a UI for this at some point

Change-Id: I74029e709a69705eba7e16f50a7fb6d4030259d1
Reviewed-on: https://gerrit.instructure.com/3138
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Zach Wily <zach@instructure.com>

config/delayed_jobs.yml.example

@@ -6,6 +6,7 @@ production:
   - queue: canvas_queue
     workers: 4
   - periodic: config/periodic_jobs.rb
+  max_run_time: 28800
 
 default:
   workers:

vendor/plugins/delayed_job/lib/delayed/pool.rb

@@ -46,6 +46,9 @@ module Delayed
           "Invalid config file #{config_filename}"
       end
       logger.auto_flushing = true if logger.respond_to?(:auto_flushing)
+      Worker::Settings.each do |setting|
+        Worker.send("#{setting}=", @config[setting.to_s]) if @config.key?(setting.to_s)
+      end
     end
 
     def environment

vendor/plugins/delayed_job/lib/delayed/worker.rb

@@ -35,7 +35,9 @@ module Delayed
   end
 
   class Worker < WorkerBase
-    cattr_accessor :min_priority, :max_priority, :max_attempts, :max_run_time, :sleep_delay, :queue, :cant_fork
+    Settings = [ :max_attempts, :max_run_time, :sleep_delay, ]
+    cattr_accessor *Settings
+    cattr_accessor :min_priority, :max_priority, :queue, :cant_fork
     self.sleep_delay = 5
     self.max_attempts = 25
     self.max_run_time = 4.hours