Process the video description using OTIO

[utsab]

Parse the video description in python and create a Timeline object with Markers to represent the chapters

Add a check before the main video description parsing logic which confirms that the video description actually is text and that it contains time stamps.

How to test:

• Verify that the Timeline object has the correct of Markers on it.
• Verify that each marker has the correct text on it.

[utsab]

Right now the OTIO timeline (.otio file) may not have the correct text for each marker.