mod_s2s: Fix logging of <stream:error> consistency with other mods `reason` was often a table, so the log said "table: 0xptr" or such. mod_c2s, mod_bosh etc logs the stream error stanza object, so better do the same. It would be nicer if this was an util.error object, but that will have to be a future change.

describe("util.poll", function ()
	it("loads", function ()
		require "util.poll"
	end);
end);