rename the exposure model export template
update the link to the exposure model export template
oq-ui-api/geonode/exposure/views.py:

Fixed a lon/lat transposition bug.
 oq-ui-client2/exposure_model_export.html:

Renamed to exposure_building_form.html.
oq-ui-api/geonode/exposure/views.py:

Renamd the building exposure export-related views.
oq-ui-api/geonode/exposure/views.py:

Added some missing underscores to the CSV header.
oq-ui-api/geonode/exposure/views.py:

Fixed a reference to a non-existent variable.
oq-ui-api/geonode/exposure/views.py:

Stubbed out the population exposure export views.
oq-ui-api/geonode/exposure/urls.py:

Cleaned up and added to url routing for the new exposure export views.
oq-ui-api/geonode/exposure/tests.py:

Updated tests per some renamed functions in views.py.
oq-ui-api/geonode/exposure/util.py, views.py:

Adjusted the population query so that it doesn't always operate on
the country level (but can work on any admin level).

This was a bug.
oq-ui-client2/src/exposure/exposure_export.js:

Refactored the client to add the population exposure export option.
oq-ui-api/geonode/exposure/forms.py:

Split forms into Building and Population.

Also changed the way we handle admin level selections (per new requirements).
oq-ui-client2/exposure_building_form.html:

Element ID updates.
oq-ui-client2/exposure_export.html:

Minor fix to the collection of URL_PARAMS, so that we can capture
strings as well (not just numbers).
oq-ui-client2/exposure_export.html:

Changed the id of the div used as a placeholder for the export forms.
oq-ui-api/geonode/exposure/views.py:

Minor fixes.
oq-ui-client2/exposure_population_form.html:

Added exposure population export form.
oq-ui-api/geonode/exposure/util.py:

Added _get_available_admin_levels query function.
oq-ui-api/geonode/exposure/util.py:

Added a query for getting all of the exposure data in a single query,
for the national level.