Fall back to ActiveSupport::JSON if no JSON.

Split result parsing into separate method.

lib/geocoder/lookups/base.rb

 require 'net/http'
-require 'json'
+unless defined? ActiveSupport::JSON
+  begin
+    require 'json'
+  rescue LoadError
+    raise LoadError, "Please install the json gem to parse geocoder results."
+  end
+end
 
 module Geocoder
   module Lookup
@@ -49,14 +55,27 @@ module Geocoder
       #
       def fetch_data(query, reverse = false)
         begin
-          JSON.parse(fetch_raw_data(query, reverse))
+          parse_raw_data fetch_raw_data(query, reverse)
         rescue SocketError
           warn "Geocoding API connection cannot be established."
         rescue TimeoutError
           warn "Geocoding API not responding fast enough " +
             "(see Geocoder::Configuration.timeout to set limit)."
-        rescue JSON::ParseError
-          warn "Geocoding API's response was not valid JSON."
+        end
+      end
+
+      ##
+      # Parses a raw search result (returns hash or array).
+      #
+      def parse_raw_data(raw_data)
+        if defined?(JSON)
+          begin
+            JSON.parse(raw_data)
+          rescue JSON::ParseError
+            warn "Geocoding API's response was not valid JSON."
+          end
+        elsif defined?(ActiveSupport::JSON)
+          ActiveSupport::JSON.decode(raw_data)
         end
       end