initial commit for video support for pbs

[mkendall07]

Type of change

• Bugfix
• Feature
• New bidder adapter
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other

Description of change

Adds video ORTB properties.

Usage:

var adUnit1 = {
    code: 'videoAdUnit',
    sizes: [400, 600],
    mediaTypes : {
        video : {
            mimes: ['video/mp4'],
            minduration : 1,
            maxduration : 2,
            protocols : [1,2],
            w : 1,
            h : 2,
            startdelay : 1,
            placement : 1,
            //other ORTB video params
        }
    },
    bids: [...]
} 

[rmloveland]

@mkendall07 does this imply a separate workflow for showing video ads if you are using Prebid Server vs. if you are getting video demand from client-side adapters? (And thus needs docs?)

[mkendall07]

@rmloveland
It's our hope that it's not a separate workflow - however, not all the pieces are in place yet (PBS support, cache etc).

From the docs perspective, I think we just need to add the ORTB properties into the video attribute (as shown above).