Version bump to 0.6.4
Version bump to 0.6.4

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