add blank History file so that rake does not complain
add blank History file so that rake does not complain

mapnik/Ruby-Mapnik,mapnik/Ruby-Mapnik,gravitystorm/Ruby-Mapnik,mapnik/Ruby-Mapnik,mapnik/Ruby-Mapnik,gravitystorm/Ruby-Mapnik,gravitystorm/Ruby-Mapnik,mapnik/Ruby-Mapnik,gravitystorm/Ruby-Mapnik,gravitystorm/Ruby-Mapnik,mapnik/Ruby-Mapnik,gravitystorm/Ruby-Mapnik