Provide example configuration to demo-stereo-odometry

[jlblancoc]

Goal: users should be able to directly test a live demo after compiling this package. (cc: @famoreno )

To do:

• [ ] Upload a .ini config file for demo-stereo-odometry, e.g. to a new root directory named tutorial, examples or alike.
• [ ] Update README.md to reflect the instructions, how to call demo-stereo-odometry with all the corresponding parameters, etc. The dataset will be large, so it's better not to include it here, but provide a download link, for example.
• [ ] Perhaps, also update README.md to show a short description of demo-stereo-odometry, its parameters, etc.
• [ ] Record a demo with demo-stereo-odometry, upload to YouTube and link it in the README. (I could do this after the other points above are done ;-) )