Show welcome to country message if user changes country.

[havard024]

• Create a GlobalStore with the purpose of sharing common store logic accross views
• Move current country from CoverageStore to GlobalStore since it's now needed for both BalanceView and CoverageView
• Add logic to cache current country so we can use it to compare if user changes country
• Create a component out of the message view so it can be reused for different types of balance screen messages