Longbow still breaks with generic executables

[jimboid]

This is evident when trialling a link with chemshell and longbow. Initial goes at launching chemshell with Longbow using a hard path triggers a python traceback

Traceback (most recent call last):
  File "/home/jimboid/.local/lib/python2.7/site-packages/longbow/corelibs/entrypoints.py", line 227, in launcher
    longbow(parameters)
  File "/home/jimboid/.local/lib/python2.7/site-packages/longbow/corelibs/entrypoints.py", line 286, in longbow
    applications.processjobs(jobs)
  File "/home/jimboid/.local/lib/python2.7/site-packages/longbow/corelibs/applications.py", line 150, in processjobs
    app = appplugins[os.path.basename(jobs[job]["executable"])]
KeyError: 'chemsh.x'

This relates to code that is trying to determine which application plugin it should use to process the commandline information. Obviously in a generic case, Longbow should just simply scan the commandline for files to upload and that is it. Rather than trying to perform any fancy per application tests, if this is required then an app extension should be made.