Add missing error messages for sucker_punch, sneakers and qu activejob adapters [ci skip]

fix error message

change raise to use rails conventions

fix misspells

activejob/lib/active_job/queue_adapters/inline_adapter.rb

@@ -14,7 +14,7 @@ module ActiveJob
       end
 
       def enqueue_at(*) #:nodoc:
-        raise NotImplementedError.new("Use a queueing backend to enqueue jobs in the future. Read more at http://guides.rubyonrails.org/active_job_basics.html")
+        raise NotImplementedError, "Use a queueing backend to enqueue jobs in the future. Read more at http://guides.rubyonrails.org/active_job_basics.html"
       end
     end
   end

activejob/lib/active_job/queue_adapters/qu_adapter.rb

@@ -23,7 +23,7 @@ module ActiveJob
       end
 
       def enqueue_at(job, timestamp, *args) #:nodoc:
-        raise NotImplementedError
+        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
       end
 
       class JobWrapper < Qu::Job #:nodoc:

activejob/lib/active_job/queue_adapters/sneakers_adapter.rb

@@ -28,7 +28,7 @@ module ActiveJob
       end
 
       def enqueue_at(job, timestamp) #:nodoc:
-        raise NotImplementedError
+        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
       end
 
       class JobWrapper #:nodoc:

activejob/lib/active_job/queue_adapters/sucker_punch_adapter.rb

@@ -23,7 +23,7 @@ module ActiveJob
       end
 
       def enqueue_at(job, timestamp) #:nodoc:
-        raise NotImplementedError
+        raise NotImplementedError, "This queueing backend does not support scheduling jobs. To see what features are supported go to http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html"
       end
 
       class JobWrapper #:nodoc: