Add insert timestamp to tag, jobtag

Fixes #43

ReleaseNotes.md

@@ -5,7 +5,7 @@ Supports job archive version 1 and database version 4.
 This is the initial release of `cc-backend`, the API backend and frontend
 implementation of ClusterCockpit.
 
-**Breaking changes**
+** Breaking changes **
 
 The aggregate job statistic core hours is now computed using the job table
 column `num_hwthreads`. In a future release this column will be renamed to
@@ -16,6 +16,16 @@ if you have exclusive jobs, only. Please be aware that we treat this column as
 it is the number of cores. In case you have SMT enabled and `num_hwthreads`
 is not the number of cores the core hours will be too high by a factor!
 
+** NOTE **
+If you are using the sqlite3 backend the `PRAGMA` option `foreign_keys` must be
+explicitly set to ON. If using the sqlite3 console it is per default set to
+OFF!  On every console session you must set:
+```
+sqlite> PRAGMA foreign_keys = ON;
+
+```
+Otherwise if you delete jobs the jobtag relation table will not be updated accordingly!
+
 **Notable changes**
 * Supports user roles admin, support, manager, user, and api.
 * Unified search bar supports job id, job name, project id, user name, and name