Support pushing results to cloud locations

[xyhuang]

We should allow user to specify a cloud location (e.g. big query) where they would like to place benchmark results, and have a reporter to push results to there.

[xyhuang]

related with #126

[Jeffwan]

@xyhuang I plan to add S3 reporter. Do you want me to Create a separate issue to track it just sync status here?

[xyhuang]

@Jeffwan Please feel free to open a new issue and sync here. As mentioned in other issue, we will commit some design improvements soon and it will be great if we can have this feature in sync. Please feel free to let me know if you want to chat about the changes before the doc goes out. thanks.