Fix SQLite

[mtudury]

This PR is a bug fix one for :

SQLite's support :

• fix : calendar not created due to affected_rows vs num_rows > 0 different behavior between MySQL and SQLite
• fix : event and calendar not created due to no default values for caldav_last_change field
• workaround : calendar never synched due to NOW() does not exist in SQLite in _is_synced. Help requested to do a better fix, at least it works.

UI :

• fix : calendar settings : Time slots per hour value was not correctly saved (need to set to value+1)