oq-ui-api/geonode/exposure/forms.py:

Render radio button widgets in exposure export form with
'class="exposure_export_widget"'.
oq-ui-client2/exposure-export-wizard-1.html:

Added an id to the 'Download' button element.
oq-ui-client2/exposure_export.html:

Implemented a more bullet-proof way of deciding when to enable the
'Download' button.
oq-ui-client2/exposure_export.html:

Refactored the sliding panel animation code and removed some suspicious
jquery monkey patching... it seems to have causing intermittent errors
and occasionally broke jquery.

See https://bugs.launchpad.net/oq-platform/+bug/1185813.