Adds a test which checks sbt reorders libs on classpath

The commment added in 6c9516bcc616953d906e1565f9f458b4f4c8ced9
was not explicit enough, which led m2eclipse-scala to reorder the classpath
manually..
Merge pull request #804 from huitseeker/unorderedlibsonClasspath

Adds a test which checks sbt reorders libs on classpath