Move JSON out of project

Massaged Maxmind data is available at the below path. Users must set the data
path before use.

`City.data_path = '/path/to/dir'`

https://s3-us-west-2.amazonaws.com/cities-gem/cities.tar.gz

.gitignore

@@ -49,3 +49,4 @@ pkg
 #*.rbc
 .ruby-gemset
 .ruby-version
+data/

cities.gemspec

@@ -20,6 +20,6 @@ txt
   s.add_development_dependency 'countries',   '~> 0.9.3'
   s.add_development_dependency 'rake'
 
-  s.files        = Dir['lib/**/*.{rb,json}'] + ['README.md', 'LICENSE.txt']
+  s.files        = Dir['lib/**/*.rb'] + ['README.md', 'LICENSE.txt']
   s.require_path = 'lib'
 end

lib/cities.rb

@@ -1,2 +1,5 @@
 require 'cities/city'
 require 'cities/country'
+
+module Cities
+end

lib/cities/city.rb

@@ -39,12 +39,10 @@ def region
 
   class << self
 
-    def path_for_country(code)
-      File.join(File.dirname(__FILE__), '..', 'data', 'cities', "#{code}.json")
-    end
+    attr_accessor :data_path
 
     def cities_in_country?(code)
-      File.exist?(self.path_for_country(code))
+      File.exist?(path_for_country(code))
     end
 
     def cities_in_country(code)
@@ -60,6 +58,17 @@ def cities_in_country(code)
       end
     end
 
+    private
+
+      def has_data?
+        data_path && Dir.exists?(data_path)
+      end
+
+      def path_for_country(code)
+        raise unless has_data?
+        File.join(data_path, "#{code}.json")
+      end
+
   end
-  
+
 end