Active Record: fix paginate_by_sql(:page => nil)

Closes #187

lib/will_paginate/active_record.rb

@@ -167,7 +167,7 @@ module BaseMethods
       # application.
       # 
       def paginate_by_sql(sql, options)
-        pagenum  = options.fetch(:page) { raise ArgumentError, ":page parameter required" }
+        pagenum  = options.fetch(:page) { raise ArgumentError, ":page parameter required" } || 1
         per_page = options[:per_page] || self.per_page
         total    = options[:total_entries]
 

spec/finders/active_record_spec.rb

@@ -212,6 +212,13 @@
       }.should run_queries(1)
     end
 
+    it "defaults to page 1" do
+      sql = "select content from topics"
+      topics = Topic.paginate_by_sql sql, :page => nil, :per_page => 1
+      topics.current_page.should == 1
+      topics.size.should == 1
+    end
+
     it "should strip the order when counting" do
       lambda {
         sql = "select id, title, content from topics order by title"