add sorting tasks by latest activity in a task

Problem

When you work in team with someone, you actively using comments for tasks, and you have many tasks. And must be except notification icon be instrument for helping us (customers) to sort tasks via last activity. That means they tasks what were updated in last order via for example added comments inside.

Vision of the feature

• Just add a flag to a task like "last_comment_date".
• Then add an extra filter which can sort in Ascending Order and Descending Order format (from tasks with latest activity to tasks with no activity at all).

It will be very helpful to always keep on a track a tasks where important some activity, where need to comment something, etc.