2nd attempt: Switch to 'trusty' distribution Travis CI builds
2nd attempt: Switch to 'trusty' distribution Travis CI builds

This switch will hopefully allow us to use a more recent version of
Java 8.

See also: https://github.com/travis-ci/travis-ci/issues/3259

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On behalf of the community, the JUnit Lambda Team thanks Klarna AB
(http://www.klarna.com) for supporting the JUnit crowdfunding campaign!
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sbrannen/junit-lambda,marcphilipp/junit-lambda,marcphilipp/junit5,junit-team/junit-lambda