Country concept

[zverok]

# Fetching
Reality.country('Ukraine')   # should return something of type Reality::Country
Reality.country('Uranus')    # should return nil... or raise some NotFound-y exception?

• Country should have at least some of useful methods from country infobox: https://en.wikipedia.org/wiki/Ukraine;
• methods like captial or currency should return some kind of generic Reality::Entity (showing it will be further queriable) -- or only in next versions?
• complex properties like leaders (concept of President of Ukraine + personality of Petro Poroshenko, concept of Prime Minister + personality) should also behave decently!

In fact, first task here is to write several "pretty" showscase-y specs, the simplest ones -- and then implement them.

[zverok]

List of fields, to be continued and reorganized:

• [x] country name
• [x] spoken/official languages
• [x] capital
• [x] area
• [x] population (estimate? or census? typically there are both)
• [x] leaders, like {president: name}
• [x] currency
• [x] phone code, iso code, TLD
• [x] continent