Add criterion crate + basic code

benches/json-benchmark.rs

@@ -0,0 +1,9 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use tests::json_parser::json_object;
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);