Make FSL melodic a recoverable and restartable task

[glatard]

It seems difficult to ensure that the Melodic code is restartable. While it creates unique directories (.ica, .ica+, etc), there is absolutely no guarantee that restarting it in the same directory won't crash or produce side effects. The best solution to date seems to be a mere deletion of the content of the working directory. Name collisions of output files created in CBRAIN should also be tested. Has to be tested for all kinds of tasks (see tests in https://github.com/glatard/cbrain-tests-fsl-melodic)