video_3s100pct_views missing from analytics API wrapper

[aniketschneider]

The video_3s100pct_views metric is no longer the current MRC standard, but the API continues to provide it under this new name. My users would like to be able to see this metric, but the current version of the API wrapper doesn't provide access to it. I've submitted a pull request to resolve this: #19

I apologize if this is redundant and the PR alone was sufficient.