tint color on ios not configurable

[firegnome]

On ios we have the problem, that the tint color of the icon is overwritten. In other words, the icon we use is white but the default tint color of ios overwrites that color. The result looks like this:

I added the second line in the fab module to achieve what i want:

newImageView = UIImageView.alloc().initWithImage(iconDrawable.ios);
newImageView.tintColor = (new colorModule.Color("#ffffff")).ios;

I can create a pull request to resolve this but i would like to hear from you what solution you would prefer. One solution could be to add a iconTintColor Property for ios.

[bradmartin]

PR gladly accepted. As long as you don't mind documenting on the README that this property is iOS only.

So document here (https://github.com/bradmartin/nativescript-floatingactionbutton#api)