use devtools to install dependencies
make it possible for serve_dir() to serve under a designated directory
a few utilities for daemonized servers: daemon_stop() and daemon_list()
make it possible to daemonize httd()
move the static server code to static.R

- renamed config() to server_config()
- added a `daemon` argument
- server_config() returns the $start_server() method
move rscript() to utils.R
closes #1: add the `in_session` to decide whether to render Rmd files in the current R session
add pre_process() and post_process() functions to dynamic_site()

then use more abstraction from server_config()
cosmetic
if in_session, and script is a function, call script(input, output)
serve_dir is a function that returns the real app function
inherit Rd from server_config()
some notes on reproducibility and new R sessions
add a vign() function to serve package vignettes without cluttering the vignettes directory with .html output files
use title case for the title per CRAN policy, and tweak description (it is not longer a "simple" server package)
suggests knitr and rmarkdown
roxygenize
rename serve.R to dynamic.R
make it possible to configure a time interval to check if the page needs to be updated every `interval` seconds
when an error occurred in building dynamic documents, stop the build, otherwise it will keep on building