changes related to commit c61b4f2edfe48369a9699a790701f313ad78b148 AsyncDrillableFilter
remove reports.fields.DatespanField and use reports.filters.dates.DatespanFilter instead
remove reports.fields.DatespanField and use reports.filters.dates.DatespanFilter instead, see commit 9b2d36b87b368a0d9bd8314d88a2ba30e7fde5f0
removed ReportSelect field, use BaseSingleOptionFilter instead, see b2d68497f121b96466af8f31e27d26d4c8393b97
removed ReportSelect field, use BaseSingleOptionFilter instead, see b2d68497f121b96466af8f31e27d26d4c8393b97
- FilterUsersField is now UserTypeFilter in reports.filters.users
- changed all references in reports from FilterUsersField to UserTypeFilter
- moved templates around for UserTypeFilter and SelectMobileWorkerField into reports/filters
- see commit c5f8fdc6734a25d8e4c413768847db66dd524f2b
- SelectMobileWorkerFilter in reports.filters.users instead of SelectMobileWorkerField
- updates all references
- see 166483c8f4fa4984282fe6ac64aa811a1fe410b9
minor refactor
- Renamed AsyncDrillableField to AsyncDrillableFilter
- Moved AsyncDrillableFilter to reports.filters.fixtures
- moved template for filter from templates/reports/fields to template/reports/filters
- renamed AsyncLocationField to AsyncLocationFilter
- moved location of AsyncLocationFitler from reports.fields to reports.filters
- moved template for this filter from reports/fields/location_async.html  to reports/filters/location_async.html
- updated all references to AsyncLocationField in commtrack / psi reports
remove reports.fields.DatespanField and use reports.filters.DatespanFilter instead
remove datespan template from old DatespanField
- rename SelectRegionField to SelectRegionFilter
- move SelectRegionFilter from reports.fields to reports.filters.select
- update references to reports.fields.SelectRegionField to reports.filters.select.SelectRegionFilter
-Renamed SelectLicenseField to SelectLicenseFilter
- Moved SelectLicenseFilter from reports.fields to reports.filters.select
- updated references of reports.fields.SelectLicenseField to reports.filters.select.SelectLicenseFilter
-Renamed SelectCategoryField to SelectCategoryFilter
- Moved SelectCategoryFilter from reports.fields to reports.filters.select
- updated references of reports.fields.SelectCategoryField to reports.filters.select.SelectCategoryFilter
-Renamed SelectOrganizationField to SelectOrganizationFilter
- Moved SelectOrganizationFilter from reports.fields to reports.filters.select
- updated references of reports.fields.SelectOrganizationField to reports.filters.select.SelectOrganizationFilter
-Renamed GroupField to GroupFilter
- Moved GroupFilter from reports.fields to reports.filters.select
- updated references of reports.fields.GroupField to reports.filters.select.GroupFilter
only show default_text if there is a value for it
-Renamed YearField to YearFilter
- Moved YearFilter from reports.fields to reports.filters.select
- updated references of reports.fields.YearField to reports.filters.select.YearFilter
remove template for YearField