Fix property name of progressBarColor

Fix property name of progressBarColor in table of default options.

README.md

@@ -123,7 +123,7 @@ Argument | Default Value | Description
 **pauseOnHover** | *true* | Pause the toast timeout while the cursor is on it.
 **resetOnHover** | *false* | Reset the toast timeout while the cursor is on it.
 **progressbar** | *true* | Enable timeout progress bar.
-**progressbarColor** | *''* | Progress bar color.
+**progressBarColor** | *''* | Progress bar color.
 **animateInside** | *true* | Enable animations of elements in the toast. 
 **buttons** | *{}* | You can specify an array of buttons.
 **transitionIn** | *'fadeInUp'* | Default toast open animation. It can be: bounceInLeft, bounceInRight, bounceInUp, bounceInDown, fadeIn, fadeInDown, fadeInUp, fadeInLeft, fadeInRight or flipInX.