Add support for pprof

This likely still needs some tuning/tweaking, but may be helpful
as we start to do more scale/performance testing of the system.

profiling.md

@@ -0,0 +1,49 @@
+# Profiling Orca
+
+If you run the Orca server with the debug flag set, not only will you get more logging output, but we enable
+remote pprof access.
+
+Links:
+* http://blog.golang.org/profiling-go-programs
+* https://golang.org/pkg/net/http/pprof/
+
+
+# Examples
+
+* First deploy orca with debug.
+* If you're using TLS (e.g., with bootstrap install) you'll need to add the certs to the local system's trusted certs (unfortunately pprof doesn't have an "--insecure" flag)
+    ```bash
+sudo bash -c "docker run --rm -it \
+        --name orca-bootstrap \
+        -v /var/run/docker.sock:/var/run/docker.sock \
+        dockerorca/orca-bootstrap \
+        dump-certs > /usr/local/share/ca-certificates/orca.crt"
+sudo update-ca-certificates
+```
+
+* Now you can point pprof at the server
+
+```bash
+ORCA=https://192.168.104.73:443
+go tool pprof ${ORCA}/debug/pprof/block
+
+web
+```
+
+That will pop up a nice SVG image on your default browser showing the accumulated blocking calls
+
+* Other URL endpoints of interest:  ("web" should produce a nice summary in each of these)
+    * go tool pprof ${ORCA}/debug/pprof/profile     - The CPU usage
+    * go tool pprof ${ORCA}/debug/pprof/heap     - The memory usage
+    * go tool pprof ${ORCA}/debug/pprof/goroutine     - The goroutine usage
+    * curl --insecure ${ORCA}/debug/pprof/   - Display the entry points (or use your browser)
+
+# Dropped nodes
+
+* It looks like nodefraction can be used to include nodes that would otherwise be dropped, but the web visualization seems to ignore it
+    ```bash
+go tool pprof -nodefraction=0.00000001 ${ORCA}/debug/pprof/block
+
+peek swarm
+```
+