Solved bug on tree generation

Found a bug on the tree generation algorithm. Contributions data structure now is local not a class attribute.

Naming Changes, Avoid some Dependencies and solved a QuotaManager Bug

QuotaManager Bug was getting the api_key directly from the environ instead of getting it from constructor.
Also Renamed some Classes to better fitting names and added some more parameters to the search_videos call to YoutubeDataAPI in order to filter better the videos that what we get.
Extracted Node-YoutubeDiscussionTreeApi, all things related to Nodes have to be don in YoutubeDiscussionTree Object.

Bug in tree equals

Solved bug of YoutubeDiscussionTree equals and added tests. Also modified the output file of serializer tests, and added some things that forgoted to add into the README.

first release

1.0.0

removed model checking to other repo