Added fuzzing code and readme.md to explain

roaring/README.md

@@ -0,0 +1,30 @@
+# The Fuzzer
+
+For complete documentation on go-fuzz, please see: https://github.com/dvyukov/go-fuzz
+
+The fuzzer in relation to the roaring package checks the `Bitmap.UnmarshalBinary` function found in `roaring.go`. In order to use the fuzzer, you can follow these steps:
+
+`cd $GOPATH/src/github.com/pilosa/pilosa/roaring`
+
+`go-fuzz-build ./`
+
+You must now make the workdir/corpus directory. This is achieved by:
+
+`mkdir workdir/corpus`
+
+The fuzzer needs some input to start the fuzzing with. Copy some sample fragments into the workdir/corpus folder. Once you have copied your sample inputs, you are ready to run the fuzzer:
+
+`go-fuzz`
+
+## Understanding the Fuzzer Output
+
+The fuzzer will output something similar to the follwoing:
+
+`2015/04/25 12:39:53 workers: 8, corpus: 124 (12s ago), crashers: 37, restarts: 1/15, execs: 35342 (2941/sec), cover: 403, uptime: 12s`
+
+The most important part of the output is the `crashers` and `cover`. The crashers records how many combinations were discovered that fail and the cover tells you how much code is being accessed.
+For a complete explanation of the output, please see: https://github.com/dvyukov/go-fuzz.
+
+The fuzzer will document the crashers in a folder labeled "crashers." It will record the fragment and the error that was produced in two separate files within this folder. This is the final product.
+
+Happy Fuzzing!

roaring/fuzzer.go

@@ -0,0 +1,12 @@
+// +build gofuzz
+
+package roaring
+
+func FuzzBitmapUnmarshalBinary(data []byte) int {
+	b := NewBitmap()
+	err := b.UnmarshalBinary(data)
+	if err != nil {
+		return 0
+	}
+	return 1
+}