i247: allow shapefile path to be used in addition to key

A path may now be passed to ShpCabinetIterator in addition to
OcgOperations for the "geom" argument.

Closes #247.
i231: generate demonstration code for geoweb integration

Initial example code for netCDF conversion to GeoJson.
Update release.org
version changes
Merge branch 'master' of https://github.com/NCPP/ocgis
doc changes.
seasonal grouping for computations #155

Tuple condition was not handled in the grouping method. The grouping
sequence is converted to a list now before attempting a 'remove'.

The string 'year' may now be included as an element as part of the
OcgOperations argument 'calc_grouping' when a seasonal grouping is
requested.
Merge branch 'master' into i183-units

Conflicts:
	src/ocgis/api/request/nc.py
	src/ocgis/exc.py
	src/ocgis/interface/base/variable.py