added new geometry for QED

The city centroids shapefile was added for the QED workshop.
time_region and time_range validation

There is a need to allow both the time_range and time_region parameters
to be passed. A validation function was written to ensure these two
overlap.
new test file for remote datasets

This test file was added to facilitate testing of remote datasets.
time range and time region together at last

Time range and time region may passed together with validation to
ensure they overlap. The time region subset is applied after the
time range.