Better task fetch timeout control

[richfitz]

~Merge after #80, contains those commits.~

This PR allows tuning of the default task wait timeout in two places:

• globally with the option rrq.timeout_task_wait
• at the rrq_controller level with the timeout_task_wait argument

It is overrideable at the point of retrieval

[codecov[bot]]

Codecov Report

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[r-ash]

Just a conflict in NEWS to sort but looks great