Change `InAppBrowser.open(url, target, options)` to get `options` as object, not string

`InAppBrowser.open(url, target, options)` currently expects `options` to be a string, formatted in a special way (no spaces).
It would be much easier to maintain this if `options` would be a plain Javascript object.

The yes|no values could be changed to true|false of course.

(During this change all options should probably also be unified to use camelCase)