[#46661033] Added "type" attribute to workflow model.
[#47173053] Added "graph" field to workflow model to store workflow graph (in the case of Galaxy workflows this is the workflow dictionary).
[#46661033, #47173053] Changed how workflows annotation is parsed. Now storing workflow dictionary as JSON in workflow model and using this information to render workflow image.
[#46661033] Adding outputs of download workflows to download list instead of adding them to the data set (as done for analysis workflows).
[#47173053] Changed download_workflow method to return JSON serialized workflow graph dictionary stored in model.
[#46661033] Changed landing page to show downloads associated with each data set.
[#46661033] No longer showing "download" analyses in list of running analyses.
Updated .gitignore.
Merge branch 'workflow_types_feature' into develop

Conflicts:
	refinery/core/views.py
Merge branch 'develop' of github.com:parklab/Refinery into develop