dropbear: Change from init.d to upstart

* dropbear.upstart taken from
  http://mailman.openwebosproject.org/pipermail/openwebos-general/2012-October/000099.html
* bbappend used instead of copying .inc and .bb as suggested
  http://mailman.openwebosproject.org/pipermail/openwebos-general/2012-November/000103.html

Open-webOS-DCO-1.0-Signed-off-by: Steve Lemke <steve.lemke@palm.com>
Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
dropbear: set DISTRO_TYPE to debug

* webos distro does not set any password and dropbear by default does
  not allow empty password and it cannot be changed in runtime config
  like in openssh.

* force DISTRO_TYPE to debug in this recipe, because
  DISTRO_TYPE ?= "${@base_contains("IMAGE_FEATURES",
  "debug-tweaks",
  "debug", "",d)}"
  does not work correctly when debug-tweaks is added to IMAGE_FEATURES
  in image recipe. It would work if you add debug-tweaks in
  EXTRA_IMAGE_FEATURES, because that's global.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>