add: rewriter logic and tests

README.md

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+# A simple Kubernetes load balancer
+
+Configures nginx to forward connections to your node IPs.
+Services should be declared as NodePort, which means that they
+open a port on all nodes. When the request lands on any node,
+it is forwarded to the correct pod via the network mesh kubernetes
+is using. In theory, there is one a hop penalty.
+
+But lets be honest. You're running with a single LB, probably a GCE free
+tier N1 VM. That extra hop doesn't matter.
+
+## Config
+
+Configure nginx to do what you want, test it. Use any Node IP for your testing.
+This tool accepts an argument (rewrite_string) which will be replaced using these rules:
+
+1. For each line that contains rewrite string:
+2. Copy the line once per node IP, replacing the string with host IPs
+