Add Context to clients / sessions.

[fancycode]

The Context will be closed when the client disconnects / the session is removed, so any pending requests can be cancelled.

[coveralls]

Pull Request Test Coverage Report for Build 9108015094

Details

• 62 of 71 (87.32%) changed or added relevant lines in 6 files are covered.
• 6 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.002%) to 54.391%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
hub.go	44	45	97.78%
clientsession.go	11	13	84.62%
grpc_remote_client.go	0	3	0.0%
virtualsession.go	0	3	0.0%

Files with Coverage Reduction	New Missed Lines	%
client.go	2	74.64%
clientsession.go	2	63.68%
grpc_remote_client.go	2	75.57%

Totals
Change from base Build 9107809001:	0.002%
Covered Lines:	8256
Relevant Lines:	15179

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💛 - Coveralls