Added support for `--deb-init FILEPATH`

See http://www.debian.org/doc/manuals/maint-guide/dother.en.html#initd
Add support for `--deb-default FILEPATH` and `--deb-upstart FILEPATH`

http://manpages.ubuntu.com/manpages/lucid/man1/dh_installinit.1.html
Merge pull request #478 from doismellburning/deb-init-config

Add init-y configuration options for Debian packages