Motion tracking demo using bokeh for live visualization

[PhilippPlank]

Issue Number: #70

Objective of pull request: Add motion tracking demo which uses bokeh for live visualization.

Pull request checklist

Your PR fulfills the following requirements:

• Issue created that explains the change and why it's needed
• Tests are part of the PR (for bug fixes / features)
• Docs reviewed and added / updated if needed (for bug fixes / features)
• PR conforms to Coding Conventions
• PR applys BSD 3-clause or LGPL2.1+ Licenses to all code files
• Lint (pyb) passes locally
• Build tests (pyb -E unit) or (python -m unittest) passes locally

Pull request type

Please check your PR type:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation changes
• Other (please describe):

What is the current behavior?

What is the new behavior?

Does this introduce a breaking change?

• Yes
• No

Supplemental information

[mathisrichter]

Some minor changes and questions.

My main concern: how are we dealing with new software dependencies? I saw at least dv and bokeh.