Brightcove player component

[mister-ben]

This is an amp-brightcove component to implement a Brightcove player as outlined in #1048.

Closes #1048.

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[cramforce]

Maybe add a link?

[cramforce]

Please add here
https://github.com/ampproject/amphtml/blob/master/test/integration/test-example-validation.js#L39
and whitelist the failure for now (because the validator was not yet updated)

[cramforce]

Up to you but a simpler or more focused example might be easier to comprehend.

[dvoytenko]

Everything looks good, but we need to fix CI tests. Please see comments above. Otherwise LGTM on my part.

[googlebot]

CLAs look good, thanks!

[mister-ben]

The tests are passing now.

[dvoytenko]

Awesome. Last request: could you please squash the commits?

[mister-ben]

Squashed commits.

[dvoytenko]

LGTM

[dvoytenko]

Merged. Thanks a lot!