last update date of the model to be easily displayable

[rajeev1]

Last refreshed date for the model. This should be easy to display on the report. This is currently available for the dashboard though. The 'report' is the one that is more frequently accessed and pinned as a full tile. currently one has to insert a calculated column in a table in the model viz. NOW () and display it in a grid and position it along with several other text boxes viz. "Updated as on", "GMT" or "IST"