Using additional root urls for localization purposes

[golopupinsky]

Proposed change allows specifying multiple root urls for easy app localization.
Additional root urls keys in settings.plist should specify language two-letter code capitalized as following "urlEN", "urlFR", "urlNL".
Upon launch app will iterate over preferred device localizations and will try to find and assign a corresponding localized root url. If no corresponding localized urls found it will use the default "url" key value.
Addresses issue #73

[gliechtenstein]

Thanks for the pull request and the idea. This inspired me to think about the problem a bit more, and I think we need to approach this from a deeper level, otherwise we will have to come up with ad hoc approaches every time we come across obstacles like this.

So my idea is two parts:

1. instead of having multiple urls, support an href attribute on the settings.plist file, which is a dictionary, and is the same href object we use all across the app. In fact we use this scheme for opening the app via url scheme support url scheme #10

2. set $env.locale global variable with the current device's locale.

When we compose these two together, we can open a home href which is relevant to the current user. The resulting settings.plist may look like this:

Let me know what you think, thanks!