The ability to customise request timeout in ConfigManager

[GordonSo]

The default settings for

• Blocking request timeout
• Polling interval
• Request timeout
  are all default to 10 seconds

Whilst the library offers the ability to override the Blocking and Polling settings, the request timeout is not exposed.
Can you confirm that this is a design decision, or would you be happy to accept our PR to expose the timeout setting also?

The reason this is important to us is because of the need to limit and have predictable message processing duration in our high-throughput system, and to de-risk ourselves from any network problem.

We would be happy to accept the risk that if we will fall back to the default variant on timeout, it can cause a discrepancy in the recorded metrics of the fallback variant being used instead of the variant that may be returned eventually; we expect this the occurrence should be rare.

[GordonSo]

Based on the helpful comment in PR #327 we learned that setting the "blocking_timeout" should be sufficient to serve our purpose.

The "request_timeout" is the polling thread timeout in the background which shouldn't be blocking.

nb: due to my limited understanding of the library, I'm just putting a timeout wrap via "Signal" on the Optimizely our function call for safe measures (see link). And I shall report back if the safe measure branch is ever required.