Breaking change to user search in latest patch release. #151

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Description

The users attribute of the server object was changed from SearchList to SearchDict. This is a breaking change that was not reflected in the version number. Furthermore this dictionary is keyed by name while the SearchList used the user object's __eq__ method to search by id or name. A basic function is now broken, namely resolving a user identity from the Slack id contained in most events.

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