[FIX] correct various date issues in reporting

* remove old 'day', 'month', 'field' and replace them by the actual
date/datetime field
* remove weird cast to char when creating the view to prevent crash
when grouping on them
* remove duplicates (such as 'creation_date' and 'create_date')
* fix typing errors (field type date defined as a datetime in the
postgres view)
* fix search view definition