Replace the country table with a static XML countries file

Storing the countries in the database is overkill, so just use a
copy of the geonames countryInfo data that is loaded into a hash
the first time it is used.

lib/country.rb

@@ -0,0 +1,38 @@
+class Country
+  attr_reader :code, :min_lat, :max_lat, :min_lon, :max_lon
+
+  def initialize(code, min_lat, max_lat, min_lon, max_lon)
+    @code = code
+    @min_lat = min_lat
+    @max_lat = max_lat
+    @min_lon = min_lon
+    @max_lon = max_lon
+  end
+
+  def self.find_by_code(code)
+    countries[code]
+  end
+
+private
+
+  def self.countries
+    @@countries ||= load_countries
+  end
+
+  def self.load_countries
+    countries = Hash.new
+    xml = REXML::Document.new(File.read("config/countries.xml"))
+
+    xml.elements.each("geonames/country") do |ele|
+      code = ele.get_text("countryCode").to_s
+      minlon = ele.get_text("west").to_s
+      minlat = ele.get_text("south").to_s
+      maxlon = ele.get_text("east").to_s
+      maxlat = ele.get_text("north").to_s
+
+      countries[code] = Country.new(code, minlat.to_f, maxlat.to_f, minlon.to_f, maxlon.to_f)
+    end
+
+    countries
+  end
+end