fix: ensure consistent use of read/write deadlines

[dnwe]

The broker.go connection doesn't consistently set Read and Write
deadlines before performing read/write operations on the net.Conn. In
various scenarios if the broker stops responding that can cause the
given connection in the client to block indefinitely

Fixes #1528

[varun06]

Looks good.

-- FAIL: TestFuncProducingSnappy (1.43s)

    metrics_test.go:160: Expected histogram metric 'request-latency-in-ms' min >= 10, got 0

    metrics_test.go:160: Expected histogram metric 'response-size' min >= 1, got 0

[dnwe]

@varun06 yeah I think that's just an unrelated flakey test as all the other travis builds in the matrix passed and I couldn't reproduce that test failing locally. I'll try and trigger a travis rerun