MINOR: spoe: add random ip-reputation service as SPOA example

This is a very simple service that implement a "random" ip reputation
service. It will return random scores for all checked IP addresses. It only
shows you how to implement a ip reputation service or such kind of services
using the SPOE.
diff --git a/.gitignore b/.gitignore
index 62f0540..7f889a0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,5 +34,6 @@
 /contrib/ip6range/ip6range
 /contrib/iprange/iprange
 /contrib/systemd/haproxy.service
+/contrib/spoa_example/spoa
 /src/dlmalloc.c
 /tests/test_hashes