calendar: Port calendar to ClutterTableLayout

We don't make use of any functionality StTable provides over
ClutterTableLayout, so port all users to the Clutter layout
in order to remove our own copy of the code.

https://bugzilla.gnome.org/show_bug.cgi?id=703833
calendar: Port EventsList to ClutterTableLayout

We don't make use of any functionality StTable provides over
ClutterTableLayout, so port all users to the Clutter layout
in order to remove our own copy of the code.

https://bugzilla.gnome.org/show_bug.cgi?id=703833