clearsightstudio/ProMotion — pull request #203 by ainame (2013-07-07 04:43:37+00:00)
Title: enhancement of Version 1.0 web screen

Hi, I want to be merged this, please.

When I have created RubyMotion app (that is called [shiori](https://github.com/ainame/Shiori)) by ProMotion v0.7.6, I created [my original webscreen module](https://github.com/ainame/Shiori/blob/master/app/screens/web_view_screen_module.rb).

I think that PM::WebScreen is more better than it.
But, my original webscreen module has some convenience methods, such as open_url, curreent_url, on_rpc_call, etc...
So, I porting some methods from my module to ProMotion::WebScreen.

I implement following methods.
* open_url(url_string)
* reuest to url in WebView
* current_url
* can get current web site url
* on_request(request, type) hook
* this hook method is convenience, when you create web bridge.
* sample code https://github.com/ainame/Shiori/blob/update_promotion/app/screens/viewer_screen.rb#L50