BLK-161 YouTube user block

Signed-off-by: Oren Leiman <oleiman@neutral.io>
BLK-161 Youtube block updates the queries list and associated internal data structures. Adds YouTubeUser block to README.md

Signed-off-by: Oren Leiman <oleiman@neutral.io>
BLK-161 Code Review changes

Signed-off-by: Oren Leiman <oleiman@neutral.io>
Merge pull request #4 from nio-blocks/feature/youtube_user

Feature/youtube user