<ticket>#624</ticket>
<ticket>#624</ticket>

core/system/linux.py:
- TestLinux.test_executable_file_in_path:
Do not rely on path to ls is always /bin/ls, which is the case on Fedora 17.

hjanime/VisTrails,hjanime/VisTrails,minesense/VisTrails,minesense/VisTrails,minesense/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,minesense/VisTrails,celiafish/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,Nikea/VisTrails,minesense/VisTrails,Nikea/VisTrails,Nikea/VisTrails,Nikea/VisTrails