Support EL and Fedora repo

- Rename apt.rb -> repo.rb.
- For EL, add EPEL repository for dependencies by default.
Deactivable by using el_add_epel: false under ceph: {} in
the chef environment.
- Handle package names difference between EL/FC and Debian.

Signed-off-by: Alexandre Marangone <alexandre.marangone@inktank.com>
Upstart and SYSV Init support

- Handles different service names between upstart
and sysvinit.
- Create mon_dir/(upstart|sysvinit) depending on
service to be used.

Signed-off-by: Alexandre Marangone <alexandre.marangone@inktank.com>