Taking request logging out of SecurityFilters
#595 - Fix issue with error icon not being shown in IE8.

Caused by an OpenLayers 2.10 bug where the loadend event isn't being generated when there are errors loading tiles in IE8.

Fixed by correcting the order of onImageLoadError and onerror event handler execution
Renamed 'TimeFilter' to 'DateFilter', for consistency.  Removed unused filter type ('datetime') from server-side code.
fixing #563 by using delayed removal for a layer that's loading
Fixed indentation.
working Groovy side changes to allow dateRange filter type to be configured for a layer
Re-added 'datetime' type - apparently it's a value which can possibly be sent back from geoserver.
Merge branches 'date_range_filter' and 'master' of https://github.com/aodn/aodn-portal into date_range_filter

Conflicts:
	grails-app/migrations/changelog.groovy
	test/unit/au/org/emii/portal/FilterControllerTests.groovy
	test/unit/au/org/emii/portal/FilterTests.groovy
removed println
Merge pull request #625 from aodn/security_filter_tidy

Taking request logging out of SecurityFilters
fixed database migration dependencies
Add some more comments explaining the why and how of the fix for #595
Incorporate review comments
database migration needed only in BuildConfig
Merge pull request #632 from aodn/database_migration_deps

fixed database migration dependencies
Merge pull request #627 from aodn/issue-595

#595 - Fix issue with error icon not being shown in IE8.
Updating indentation that hasn't been fixed before
Refactor in order to prepare for DateRangeFilterPanel implementation.

- renamed *Filter to *FilterPanel (to be more consistent with how other classes are named).
- calculating CQL on the fly (rather than caching in BaseFilter.CQL)
- various other cleanups.
Merge pull request #628 from aodn/date_time_filter_naming_consistency

Renamed 'TimeFilter' to 'DateFilter', for consistency.  Removed unused f...
review changes. Rename variables, validation in groovy form, changeset typo