1009617 - limit options for repo sync and publish history now states the...

... default limit is 5

https://bugzilla.redhat.com/show_bug.cgi?id=1009617

The default behaviour for the history REST API has also changed. Previously, if no limit was specified then a limit of 5 would be imposed. Now, if a limit is not given, the entire history list is returned. This PR also includes REST API documentation for repository history.