Added "viewer" parameter to html_print
Added "includeSrcDir" parameter to htmlDependency
Revert "Added "includeSrcDir" parameter to htmlDependency"

This reverts commit 161929f073394903db8c6813e12b663434bb359f.

The addition of a new parameter breaks rmarkdown because of rmarkdown's
aggressive validation.
factor save_html function out of print_html
bump version
Merge branch 'master' of https://github.com/rstudio/htmltools