Fix Arch Linux rosdep mappings.

## Fixed

* python2-argparse is now part of python2,
* fixing some python2/3 errors (lots of packages need to be checked and changed),
* using [`gazebo`](https://aur.archlinux.org/packages/gazebo/) (release package) rather than [`gazebo-hg`](https://aur.archlinux.org/packages/gazebo-hg/) (upstream package). Note that `gazebo-hg` does provide `gazebo` so users can still choose between these two options.
* `festival-kallpc16k` is now named [`festival-english`](https://www.archlinux.org/packages/community/any/festival-english/).
* `python-gst` is named `gstreamer0.10-python`

## Known remaining errors

* ~~compilation fails with yaml-cpp 0.5 so we stick with version 0.3~~ (cf. [discussion](https://github.com/ros/rosdistro/pull/2891#discussion-diff-8950120)) packages will still need [yaml-cpp0.3](https://aur.archlinux.org/packages/yaml-cpp0.3/) until everything is fixed in ROS packages,
* Ogre 1.9 is currently being fixed for gazebo/rviz so [ogre-1.8](https://aur.archlinux.org/packages/ogre-1.8/) is being used instead for now.