[Pharo-project] [Failing Tests] Cleaned up failing test serialization

Hi, To make it easy to explore why a test fails on the test server we serialize the stack of falling tests. With two changes this has now gotten much easier: 1) Drag and Drop support for .fuel file Just drag the file to the Pharo Desktop --> Debugger opens 2) There where always a lot of fuel files. Reason: Expected failures where serialized, too. This is now changed and the only serialized tests are those that failed. E.g for linux, you can download them here: https://ci.inria.fr/pharo/job/Pharo-2.0-Tests/lastCompletedBuild/label=linux... Marcus