Launch shiny-server through shim binary

This replaces the bin/shiny-server bash script we were previously using.
The problem with the former was that it caused at least one fork, which
confused upstart (I tried using "expect" directives to get it to detect
the right PID but the obvious incantations were not working).

Using the new bin/shiny-server binary, we can optionally launch
daemonized by using --daemonize, or just run direct which does not fork
at all.

Note that the upstart/init.d scripts may need to be updated to take full
advantage.
Add missing file
Add pidfile option
Merge remote-tracking branch 'jcheng5/binary-launcher'

Conflicts:
	CMakeLists.txt
	config/upstart/shiny-server.conf
Fix init.d script for RedHat
Fix post-install script for RedHat
Improve init.d script for redhat

- Proper echoing
- Reload support
Jenkins passes BUILD_NUMBER, not BUILD_VERSION
Move node install to ./ext instead of ./bin
Merge branch 'master' of github.com:rstudio/shiny-server