Feature request: Add change log for titles

[jareddreyer]

Every time a movie or television show is updated a change log commit record should be added to its record.

This way a user can see what has changed and what history the title had.

E.g. setup new column "log" and use onBeforeWrite() to save any log information.

[jareddreyer]

This feature could be further developed when SS4 is implemented to using the info in versioned dataobjects.

[jareddreyer]

With #33 this now has a LastFetched date and with the hydrationjob a db record is recorded.
Technically nothing if the metadata is deleted and refetched howver.
Still need something.