allow developer to opt into strictly enforced region choices (bug 896613)

https://bugzilla.mozilla.org/show_bug.cgi?id=896613

# Free
![](http://f.cl.ly/items/2j0x3v2U2f0l2X3o0T2l/Screen%20Shot%202013-10-29%20at%206.04.42%20PM.png)
![](http://f.cl.ly/items/182h182M0T0U1E3F0D3O/Screen%20Shot%202013-10-29%20at%206.04.48%20PM.png)

# Paid
![](http://f.cl.ly/items/1v3w2n273R0a3n3h3y03/Screen%20Shot%202013-10-29%20at%206.04.26%20PM.png)
![](http://f.cl.ly/items/2y463q1n1e1b3a0N3j1N/Screen%20Shot%202013-10-29%20at%206.04.32%20PM.png)