cp#1000077: Set 'modified' document property more consistently.

Update document info at one place, so that it works for other formats
like .doc, .docx, ... too.

Change-Id: If71799b491d2210f0d3bdbdb05f91f26c986a260
Use proper constructor to fill with system time.

Probably 86adb5cacb4fe3e7fb869299447da5876f0da30d did not mean to change
the behaviour here.

Change-Id: If39c150973c502323b3c785a9738cf65cdd74e5d
Update also revision and editing time when setting 'modified' properties.

Change-Id: Id756ef6dd62ca8df2e62265b9cc930f07d13f2e3