Forwarding events carried over WebSockets reconnect doesn't work

[Xemdo]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Problem/Feature

See #315.

NOTE: Overall this is a bigger tech debt issue that I described in #317. This fix resolves the issue for end-users, but does not fix the underlying mistakes that led to this issue.

Description of Changes:

• Fixed issue by removing the subscription object's awareness of the client name. It already lived in the map that held the Subscription objects, so we will rely on this from now on to avoid duplicating info.

Checklist

• My code follows the Contribution Guide
• I have self-reviewed the changes being requested
• I have made comments on pieces of code that may be difficult to understand for other editors
• I have updated the documentation (if applicable)