providing Max time Unit feature by attribute

Hi Sid,

I have included max-time-unit option to timer. Application can display time in mm:ss instead of hh:mm:ss through this option.

Could you please review it. I am very new to this gitHub and everything. please let me know if there's a mistake or any change you want. 
I have updated example page with attribute table and added e2e test scenario.

thanks and regards,