feat(integration_test) add make task to perform benchmarks in docker env

pprof cannot be used reliably on OS X. This provides two make tasks to
collect and analyze profiling data.

To run profiling in a dockerized linux environment...
```
make // or `make collect`
```

To analyze results on host machine...
```
make analyze
```

@jbenet @whyrusleeping

epictest/Makefile

+# This Makefile provides a way to really simple way to run benchmarks in a
+# docker environment.
+
+IMAGE = jbenet/go-ipfs-bench
+CONTAINER = go-ipfs-bench
+PACKAGE = epictest
+PACKAGE_DIR = epictest
+BUILD_DIR = ./build/bench
+CONTAINER_WORKING_DIR = /go
+CPU_PROF_NAME = cpu.out
+
+all: collect
+
+collect: clean build_image run_profiler cp_pprof_from_container
+
+cp_pprof_from_container:
+	docker cp $(CONTAINER):$(CONTAINER_WORKING_DIR)/$(CPU_PROF_NAME) $(BUILD_DIR)
+	docker cp $(CONTAINER):$(CONTAINER_WORKING_DIR)/$(PACKAGE).test $(BUILD_DIR)
+
+build_image:
+	cd .. && docker build -t $(IMAGE) .
+
+run_profiler:
+	docker run --name $(CONTAINER) -it --entrypoint go $(IMAGE) test ./src/github.com/jbenet/go-ipfs/$(PACKAGE_DIR) --cpuprofile=$(CPU_PROF_NAME)
+
+
+clean:
+	docker rm $(CONTAINER) || true
+	rm -rf $(BUILD_DIR)
+
+analyze:
+	go tool pprof $(BUILD_DIR)/$(PACKAGE).test $(BUILD_DIR)/$(CPU_PROF_NAME)