Fix tests and resolve a bug in ExecutionBroadcaster

[pnezis]

Includes the following changes:

• Make all tests work again (#466) (had to include :crash_reason in logger metadata, and remove the custom :crash_reason from log_exception
• Fix a bug in ExecutionBroadcaster . In case of invalid timezone no state was returned and as a result the GenServer was crashing:

22:41:29.638 [error] Invalid Timezone "foobar" provided for job :test.
22:41:29.655 [error] GenServer Jobex.Scheduler.ExecutionBroadcaster terminating
** (FunctionClauseError) no function clause matching in Quantum.ExecutionBroadcaster.sort_state/1
    (quantum) lib/quantum/execution_broadcaster.ex:299: Quantum.ExecutionBroadcaster.sort_state(:ok)
    (quantum) lib/quantum/execution_broadcaster.ex:170: Quantum.ExecutionBroadcaster.handle_event/2
    (quantum) lib/quantum/execution_broadcaster.ex:91: anonymous fn/2 in Quantum.ExecutionBroadcaster.handle_events/3
    (elixir) lib/enum.ex:1948: Enum."-reduce/3-lists^foldl/2-0-"/3
    (quantum) lib/quantum/execution_broadcaster.ex:90: Quantum.ExecutionBroadcaster.handle_events/3
    (gen_stage) lib/gen_stage.ex:2395: GenStage.consumer_dispatch/6
    (gen_stage) lib/gen_stage.ex:2574: GenStage.take_pc_events/3
    (stdlib) gen_server.erl:637: :gen_server.try_dispatch/4

Closes #466

[coveralls]

Pull Request Test Coverage Report for Build 414bee22b4d6846254a703b342587281fcdb595c-PR-468

• 3 of 5 (60.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.4%) to 86.188%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/quantum/executor.ex	2	4	50.0%
<!--	Total:	3	5	60.0%	-->

Totals
Change from base Build 5c3e4a2b826c1f62256ca734506af6633d44b17c:	-0.4%
Covered Lines:	312
Relevant Lines:	362

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💛 - Coveralls

[maennchen]

@pnezis Thanks a lot again!