Initial OpenEmbedded support for rosdistro

  * Requires related changes in rospkg, rosdep
    ros-infrastructure/rospkg#166
    ros-infrastructure/rosdep#673
  * Let us map the generic system dependency name into a recipe name
    available from OE layer index at http://layers.openembedded.org
  * Mapping is based on PACKAGE_ARGUMENT free form format of
    <package>@<meta-layer>, where <package> resides in the OE <meta-layer>
  * Please see the proposal below:
    https://discourse.ros.org/t/a-proposal-for-a-superflore-oe-recipe-generation-scheme/8401