add http protocol to host if user did not enter it

If user did not enter the protocol in the field, the `iframe` source will become a simple string and will start to seach the file with host name on server.

For example:
* Type `getbootstrap.com`
* Browser throw error that file `getbootstrap.com` is not on server(in root directory of `IsRespo`)
* `iframe` element is not loaded or shows an error 'smile' :ghost: