* use session context manager
* contextlib2 added to requirements.txt
* Fixing error: Import statements are in the wrong order. from contextlib2 import contextmanager should be before import sqlalchemy
* Fixing return inside generator
* fixed C812 missing trailing comma
* E501 line too long
* fixed E127 continuation line over-indented for visual indent
* E722 do not use bare except
* reorganized imports
* added context manager contextlib2.contextmanager
* fixed import ordering
* DECKGL integration
Adding a new set of geospatial visualizations building on top of the
awesome deck.gl library. https://github.com/uber/deck.gl
While the end goal it to expose all types of layers and let users bind
their data to control most props exposed by the deck.gl API, this
PR focusses on a first set of visualizations and props:
* ScatterLayer
* HexagonLayer
* GridLayer
* ScreenGridLayer
* Addressing comments
* lint
* Linting
* Addressing chri's comments