Do we want to store values that are not readable for humans as config values ?

When all are checked it looks like this:
MariaDB [owncloud]> select * from oc_preferences;
```
+--------+----------------+----------------------------------+------------------------------------------------------------------------+
| userid | appid          | configkey                        | configvalue                                                            |
+--------+----------------+----------------------------------+------------------------------------------------------------------------+
| root   | activity       | notify_email                     | a:0:{}                                                                 |
| root   | activity       | notify_stream                    | a:8:{i:0;i:4;i:1;i:5;i:2;i:3;i:3;i:8;i:4;i:1;i:5;i:6;i:6;i:2;i:7;i:7;} |
```

No idea what "i" is and why it is repeated.
I'd think that there would simply be a comma separated list of notification types like `share_new,share_newfile,share_filechanged, share_filedeleted`