Add a yolo-v3 example. (#528)

* Add a couple functions required for yolo.

* Add the yolo-v3 example.

* Add minimum and maximum.

* Use the newly introduced maximum.

* Cuda support for min/max + add some testing.

* Allow for more tests to work with accelerate.

* Fix a typo.

candle-examples/examples/bert/main.rs

@@ -1,5 +1,8 @@
 #[cfg(feature = "mkl")]
 extern crate intel_mkl_src;
+
+#[cfg(feature = "accelerate")]
+extern crate accelerate_src;
 mod model;
 
 use anyhow::{anyhow, Error as E, Result};