'./cruise.rb --all' does not work

    $ git clean -fdx
    $ ./cruise.rb  --all
    ...
    ./cruise.rb:67:in `sh': Command './trema killall' failed! ...
'./cruise.rb' displays 'coverage = 0.0%' and returns error status (255).

    $ git clean -fdx
    $ ./cruise.rb
    ...
    Overall coverage = 0.0% ...

    ERROR
Merge pull request #354 from sugyo/feature/patch_of_cruise

quick hack of 'cruise.rb'