Docs fixes, survey and 2.2 rc version bump

Version bump v2.1.1

README project description and 2.1 features, version bump

Add toJSON() method to all new 2.0 types NODEJS-98

Links to 2.0 documentation and version bump

Readme: improved prepared statements and client#stream()

- Version bump

Prevent pool for returning connections that are not yet opened NODEJS-75

Version bump

Add FAQ to README

README: remove html comments