Fixes for OpenTok V2.2

The wrapper functions included in this meteor package needed a few more updates in order to make them compatible with the new NPM OpenTok client V2.2

I've updated the 'OpenTok' constructor to match the new version.

I've updated the createSession function wrapper to be compatible with v2.2

I've updated the generateToken function wrapper to be compatible with v2.2

I've removed the deprecated getArchiveManifest function wrapper and added new ones for v2.2

I've removed the RoleConstants which are no longer part of the NPM library for v2.2

I've updated the Readme.md to reflect these changes.