Make BlueCloth and YARD gem development dependencies instead of runtime dependencies
Make BlueCloth and YARD gem development dependencies instead of runtime dependencies

* BlueCloth is not installable on Windows
* We don't care enough about building local docs for this gem to fuss about the format
* If YARD and BlueCloth are already installed, the docs will build correctly anyway
paolomainardi/htty,shaunstanislaus/htty,ilesan-ypg/htty,Ribeiro/htty,bradparks/htty,lanastasov/htty,yous/htty,pepijnve/htty,shekkbuilder/htty,dibenso/htty