Use separate :offset and :limit query options.

PostgreSQL doesn't support the "X,Y" format for the LIMIT clause, and this
is proper use of ActiveRecord anyway.

In response to bug reported by Github user kenzie.

lib/geocoder.rb

@@ -51,7 +51,7 @@ module ClassMethods
     # 
     # +order+     :: column(s) for ORDER BY SQL clause
     # +limit+     :: number of records to return (for LIMIT SQL clause)
-    # +offset+    :: number of records to skip (for LIMIT SQL clause)
+    # +offset+    :: number of records to skip (for OFFSET SQL clause)
     #
     def near_scope_options(latitude, longitude, radius = 20, options = {})
       if ActiveRecord::Base.connection.adapter_name == "SQLite"
@@ -88,7 +88,8 @@ def full_near_scope_options(latitude, longitude, radius, options)
           coordinate_bounds(latitude, longitude, radius),
         :having => "#{distance} <= #{radius}",
         :order  => options[:order],
-        :limit  => limit_clause(options)
+        :limit  => options[:limit],
+        :offset  => options[:offset]
       }
     end
 
@@ -106,7 +107,8 @@ def approx_near_scope_options(latitude, longitude, radius, options)
           ["#{lat_attr} BETWEEN ? AND ? AND #{lon_attr} BETWEEN ? AND ?"] +
           coordinate_bounds(latitude, longitude, radius),
         :order  => options[:order],
-        :limit  => limit_clause(options)
+        :limit  => options[:limit],
+        :offset  => options[:offset]
       }
     end
 
@@ -125,16 +127,6 @@ def coordinate_bounds(latitude, longitude, radius)
         longitude + (radius / factor)
       ]
     end
-
-    ##
-    # Build the limit clause for a query based on the same options hash
-    # passed to the x_near_scope_options methods.
-    #
-    def limit_clause(options)
-      if options[:limit] or options[:offset]
-        "#{options[:offset].to_i},#{options[:limit].to_i}"
-      end
-    end
   end
 
   ##