BatchesController#synchronize should flash and exit if the batch is already synchronized

[hackartisan]

abid/app/controllers/batches_controller.rb

Lines 49 to 50 in 98e92f8

	@batch = Batch.find(params[:id])
	@batch.synchronize

batch in question on #121 was successfully synchronized at some point, this would prevent repeated attempts in the case where the request goes through successfully but the load balancer errors.