KeyError: 'location' - Cannot make job: 'location'

Looks like i found an other bug while writing these CWL files:

https://github.com/gijzelaerr/vermeerkat-cwl/tree/master/cwl

```
.virtualenv/bin/cwl-runner --outdir results --cachedir cache cwl/workflow.cwl cwl/job.cwl
.virtualenv/bin/cwl-runner 1.0.20170223161812
Resolved 'cwl/workflow.cwl' to 'file:///home/gijs/Work/vermeerkat-cwl/cwl/workflow.cwl'
[job curl] Using cached output in /home/gijs/Work/vermeerkat-cwl/cache/175791fc94a768e7e925838df7b083b2
[step curl] completed success
[job h5toms] Using cached output in /home/gijs/Work/vermeerkat-cwl/cache/106bf4457e4f2930c4189f9e7158d0ed
[step h5toms] completed success
Unexpected exception
Traceback (most recent call last):
File "/home/gijs/Work/cwltool/cwltool/workflow.py", line 587, in job
**kwargs):
File "/home/gijs/Work/cwltool/cwltool/draft2tool.py", line 190, in job
separateDirs=False)
File "/home/gijs/Work/cwltool/cwltool/pathmapper.py", line 150, in __init__
self.setup(dedup(referenced_files), basedir)
File "/home/gijs/Work/cwltool/cwltool/pathmapper.py", line 104, in dedup
if r["location"] not in marksub and r["location"] not in markdup:
File "/home/gijs/Work/vermeerkat-cwl/.virtualenv/local/lib/python2.7/site-packages/ruamel/yaml/comments.py", line 595, in __getitem__
return ordereddict.__getitem__(self, key)
KeyError: 'location'
[step rfimasker] Cannot make job: 'location'
```