Remove statement that TweetStream is not 2.0.0-compatible

This has been fixed since the 2.6.0 release, see: https://github.com/tweetstream/tweetstream/blob/master/CHANGELOG.md#version-260

Also, the referenced issue has been closed.

I'm not sure what your current stance is on using TweetStream, but 2.0.0 compatibility seems to no longer be an issue.