Fix rake task to populate from wikipedia and current_currency implementation

#1: Wikipedia updated layout. Update rake task to reflect those changes.

#2: The current_currency implementation in 789f0aa14a returns the currency object. It worked in my development environment but failed to work on heroku.

Log from heroku:
2013-07-22T14:33:03.458986+00:00 app[web.1]: Started GET "/" for 103.1.69.251 at 2013-07-22 14:33:03 +0000
2013-07-22T14:33:03.485321+00:00 app[web.1]:
2013-07-22T14:33:03.485321+00:00 app[web.1]: ActiveRecord::StatementInvalid (PG::Error: ERROR:  operator does not exist: character varying = integer
2013-07-22T14:33:03.485321+00:00 app[web.1]:                                                              ^
2013-07-22T14:33:03.485321+00:00 app[web.1]:   vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1161:in `exec'
2013-07-22T14:33:03.485321+00:00 app[web.1]: : SELECT  "spree_orders".* FROM "spree_orders"  WHERE "spree_orders"."id" = 1 AND "spree_orders"."currency" = 104 LIMIT 1):
2013-07-22T14:33:03.485321+00:00 app[web.1]: HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.

Fixed current_currency to return currency char code instead of the object itself. Works on Heroku now.