Remove nominatum.rb's dependence on Rails

The user_agent and user_agent_email are now set as class instance
variables in config/initializers/nominatim.rb.

config/initializers/nominatim.rb

@@ -1 +1,4 @@
 require 'nominatim'
+
+Nominatim.user_agent = Growstuff::Application.config.user_agent
+Nominatim.user_agent_email = Growstuff::Application.config.user_agent_email

lib/nominatim.rb

@@ -1,4 +1,3 @@
-require 'rails'
 require 'open-uri'
 require 'json'
 
@@ -6,7 +5,11 @@ class Nominatim
 
   # class-level instance variable, see
   # http://www.railstips.org/blog/archives/2006/11/18/class-and-instance-variables-in-ruby/
-  class << self; attr_accessor :in_testing end
+  class << self
+    attr_accessor :in_testing
+    attr_accessor :user_agent
+    attr_accessor :user_agent_email
+  end
   @in_testing = false
 
   def self.geocode(place)
@@ -15,8 +18,8 @@ class Nominatim
     end
     json = open(
       URI.escape("http://nominatim.openstreetmap.org/search/#{place}?format=json&limit=1"),
-      "User-Agent" => Growstuff::Application.config.user_agent,
-      "From" => Growstuff::Application.config.user_agent_email
+      "User-Agent" => user_agent,
+      "From" => user_agent_email
     ).read()
     location = JSON.parse(json)
     if location && location[0]