Remove AkkaSpec's EventFilter 

Fixes #377

Removes EventFilter from AkkaSpec and uses TestKit's

Dependent on #412 __Installs Akka.TestKit.TestEventListener as default logger for TestKit__. This the first commit shown.

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https://github.com/HCanber/akka.net/commit/a2c1a72364fa8944a80e58385f4adca5aab54828 __Remove EventFilter from AkkaSpec and use TestKit's__

__Do not merge this before #412__