Create BindValidate for context

[hayeah]

Bind and Validate are both customizable. It might be nice to provide a sugar method to do both:

func (c *Context) BindValidate(ptr interface{}) error {
	err := c.Bind(c)
	if err != nil {
		return err
	}

	return c.Validate(ptr)
}

[hayeah]

I just realized that I can do this easily with CustomBinder:

func (cb *CustomBinder) Bind(i interface{}, c echo.Context) (err error) {
	b := &echo.DefaultBinder{}

	if err = b.Bind(i, c); err != nil {
		return
	}

	return validate.Struct(i)
}