Add additional fields to printout

[mstarke]

There are two fields that should be added to the print out below the "overall time" next to the bar chart:

• validated by ,
• acknowledge/approved by ,

The first field is for the person that booked the hours to commit to the bookings, or for a representative The second field is for the client to signal it's ok and thus allow the hours to be billed.

[jume-dev]

Valid point, but i am not sure if we should simple include it like that or make it customizable. Let's continue our discussion on the new version: hicknhack-software/redmine_hourglass#6