Your R Markdown document correctly produces a data.csv and that is made available in the same output directory as the rendered HTML. I took your Rmd, deployed to one our development servers, and can get the CSV file by visiting the link.
Could you confirm your version of the rmarkdown package with packageVersion("rmarkdown") - at least 1.8.6 is required.
Also look at the version of RStudio Connect - output file support was added with version 1.6.4. http://docs.rstudio.com/connect/news/#rstudio-connect-1.6.4
I'm guessing that you are trying to deploy to an older Connect version - an old rmarkdown would err on the output_metadata reference.
Please let us know if you continue to have trouble producing output files.