MINOR/DOC: spoe-server: Add documentation

This is the documentation and examples.
diff --git a/contrib/spoa_server/print_r.lua b/contrib/spoa_server/print_r.lua
new file mode 100644
index 0000000..2fa57e7
--- /dev/null
+++ b/contrib/spoa_server/print_r.lua
@@ -0,0 +1,68 @@
+function color(index, str)
+	return "\x1b[" .. index .. "m" .. str .. "\x1b[00m"
+end
+
+function nocolor(index, str)
+	return str
+end
+
+function sp(count)
+	local spaces = ""
+	while count > 0 do
+		spaces = spaces .. "    "
+		count = count - 1
+	end
+	return spaces
+end
+
+function print_rr(p, indent, c, wr)
+	local i = 0
+	local nl = ""
+
+	if type(p) == "table" then
+		wr(c("33", "(table)") .. " " .. c("34", tostring(p)) .. " [")
+
+		mt = getmetatable(p)
+		if mt ~= nil then
+			wr("\n" .. sp(indent+1) .. c("31", "METATABLE") .. ": ")
+			print_rr(mt, indent+1, c, wr)
+		end
+
+		for k,v in pairs(p) do
+			if i > 0 then
+				nl = "\n"
+			else
+				wr("\n")
+			end
+			wr(nl .. sp(indent+1))
+			if type(k) == "number" then
+				wr(c("32", tostring(k)))
+			else
+				wr("\"" .. c("32", tostring(k)) .. "\"")
+			end
+			wr(": ")
+			print_rr(v, indent+1, c, wr)
+			i = i + 1
+		end
+		if i == 0 then
+			wr(" " .. c("35", "/* empty */") .. " ]")
+		else
+			wr("\n" .. sp(indent) .. "]")
+		end
+	elseif type(p) == "string" then
+		wr(c("33", "(string)") .. " \"" .. c("34", p) .. "\"")
+	else
+		wr(c("33", "(" .. type(p) .. ")") .. " " .. c("34", tostring(p)))
+	end
+end
+
+function print_r(p, col, wr)
+	if col == nil then col = true end
+	if wr == nil then wr = function(msg) io.stdout:write(msg) end end
+	if col == true then
+		print_rr(p, 0, color, wr)
+	else
+		print_rr(p, 0, nocolor, wr)
+	end
+	wr("\n")
+end