adding spec test to ensure map keys are strings
adding spec test to ensure map keys are strings

sferik/yajl-ruby,brianmario/yajl-ruby,tenderlove/yajl-ruby,sferik/yajl-ruby,sferik/yajl-ruby,mrkn/yajl-ruby,brianmario/yajl-ruby,tenderlove/yajl-ruby,brianmario/yajl-ruby