Remove references to queue in Zaqar's description

Zaqar is a messaging service which provides support for different
messaging patterns and messaging related semantics. Mentioning `queue`
in the service codename and description misleads people from what the
service goal actually is.

Change-Id: I09df25e0bc9cf1804ea4db67271fb55d1dcce30d
Merge "Remove references to queue in Zaqar's description"