cleanup
adding feedback modal, fixes #32, #33, #34, #35
erasing comment ifeld when done submitting
getting list of potential filters from proxy/events/get_filters
updating filter tab layout

removing Marine Debris theme from Data Tab, adding those layers to
Filter Tab, adjusting the Filter Tab layout
preventing dynamic adjustments to filterLayers
styling the date range inputs
just a little work on the update filter button -- will wrap up later
fixing typos
adding marine debris types to Beach Cleanup filter

Update Filter button now includes date ranges and flat list of debris
types (still no ontology).
Currently using complete OpenLayers library - still need to rebuild
with Strategy class included (see changes to map.js).
Also limiting Fiter tab layers to Beach Cleanups (just to simplify
things for the moment -- see server.js).
adding ontology app with Term model

in preparation for the ontology implementation
updating OpenLayers build to work with Clustering Strategy

(now includes Cluster.js)
adding OpenLayers build libraries
adding Marine Debris layers back onto the Data Tab
Added django-mptt to requirements file.
Added an RDFConcept model to mimic the graph layout of RDF as a tree.
Added management structure for rdf syncing to local DB.
Initial debug commit for the syncrdf command.
Fix for awkwardly sized filter on my screen.
Added RDFConcept migrations.

- Also added the ontology app to the list of installed apps.