I'd like to be able to track the history of manipulations done on series
(and probably its patches as well). To start with, I'm only interested
in when series are created so I can export a RSS feed containing the
new series.

For the curious mind, a full event table for just one field seems a bit
overkill. I have to mind to attach more properties to events. For
instance link a state to an event so we can generically set the state of
a series/patch when a certain event is created.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>