add autoflush option to Log::Log4perl::Appender::Screen

[abraxxa]

Closes #115

[abraxxa]

As there seems to be no existing tests for this appender, I haven't added one for the new option.

[abraxxa]

We need this support as soon as possible, can you please look into it and merge and release if ok? Thanks!

[coveralls]

Pull Request Test Coverage Report for Build 2424909462

• 2 of 5 (40.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 89.811%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/Log/Log4perl/Appender/Screen.pm	2	5	40.0%
<!--	Total:	2	5	40.0%	-->

Totals
Change from base Build 2424878188:	-0.02%
Covered Lines:	2371
Relevant Lines:	2640

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💛 - Coveralls

[mohawk2]

Thanks!