Solution: Implement Safer Run Strategies

[maennchen]

Merge #351 first

Fix for #312

It was quite hard to prevent BC breaks. I think it would be the time soon to think about cleaning up the code and think of a cleaner way to implement the run strategies while keeping #241 in mind.

[coveralls]

Pull Request Test Coverage Report for Build 786

• 15 of 24 (62.5%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-1.7%) to 83.127%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/quantum/executor_supervisor.ex	1	2	50.0%
lib/quantum/run_strategy/all.ex	0	2	0.0%
lib/quantum/executor.ex	2	8	25.0%

Files with Coverage Reduction	New Missed Lines	%
lib/quantum/executor_supervisor.ex	1	60.0%

Totals
Change from base Build 785:	-1.7%
Covered Lines:	335
Relevant Lines:	403

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💛 - Coveralls