Updated example of creating a new loop.

Using uv_loop_new() to create a new event loop is now deprecated. 

From uv.h:

/*
 * Allocates and initializes a new loop.
 * NOTE: This function is DEPRECATED (to be removed after 0.12), users should
 * allocate the loop manually and use uv_loop_init instead.
 */
UV_EXTERN uv_loop_t* uv_loop_new(void);