Added /etc/rc.d/init.d/supervisor for CentOS

Tested on CentOS 5.9 and 6.3
Use the CentOS init file on RedHat and Fedora systems

Removed repeated templates by placing platform specific templates in
default/<family>.
Use attributes to find the supervisord executable for init scripts

The location of the supervisord executable depends on whether
python was installed from source or from packages.
Switch to using the same code path for the non-smartos platforms.
Rename the redhat templates directory to rhel.
Make sure start and stop commands end with a newline on failure.
Make start return 0 if the service is already started.
Change stop not to display FAILED if the service is already stopped.
Indicate that the supervisor service supports the restart action.

Otherwise, the restart command in the init scripts are not used.
Improve platform-handling code after feedback from @borntyping.
Add myself to the README.
Add the amazon platform.
Change the name of the lock file from supervisor to supervisord.
Add code comments re: status() return values.
Exit with status code 3 for an unimplemented feature.
Update metadata and README to include RHEL platforms
Merge pull request #32 from borntyping/master

[COOK-3891] Add init scripts for Centos, RedHat and Fedora