Add support for sphinx documentation

[ayrton04]

Making a start at Sphinx documentation for this package. If anyone is aware if rosdoc works with metapackages, I can get rid of fuse_doc and just put this in the fuse package itself. But I was under the impression that wasn't supported by metapackages.

My plans going forward will be to:

• For the tutorial I added, I want to upload the bag I used to an S3 bucket and make it publicly available
• Add doxygen documentation via rosdoc_lite for every package in the metapackage
• Document all the options for all the different models, sensors, etc.
• Add more advanced tutorials

But we'll do all of that in future PRs. For now, this should serve as a decent starting point.

[ayrton04]

OK, I believe I've addressed all the PR feedback. I also uploaded a bag file and rviz display (in a .tar.xz file) to support the tutorial.

[ayrton04]

@svwilliams, any objection to also moving all of your .md documentation files over to this as well? Or do you want that stuff to live in the repo? Obviously not for this PR.

[efernandez]

I haven't run the tutorial, but it LGTM