Support VideoJS v8

[developher-net]

When VideoJS v8 is used, unit tests fail to pass. See #1045

https://videojs.com/guides/videojs-7-to-8/

Things to investigate:

• Dropped IE 11 support
• Deprecated use of videojs.extend()
• Newly deprecated functions
• Old deprecated functions
• Aria attributes
• firstplay event

[developher-net]

videojs.extend() is not being used. We're already using the extends keyword instead

[developher-net]

None of the newly deprecated functions are used in this plugin

[developher-net]

The following old deprecated functions might be used in unit tests:

• hasClass
• getAttributes

The following old deprecated methods are used in the plugin:

• plugin

[developher-net]

The firstplay event is not used in this plugin

[developher-net]

This plugin is not currently providing any logic around aria attributes