Fix validate date for poll

[fastnef2001]

• [x] When create new poll

Current Date < Start date < Sub end date < Final end date

• [x] When edit poll

Situation 1: Current date < start date. -----> Don't allow create new poll Allow delete this poll Allow edit start date, sub end date, final end date

Situation 2: start date <= current date < subend date -----> Don't allow create new poll Don't allow delete this poll Allow edit sub end date, final end date Don't allow edit start date unused -> used

Situation 3: subend date <= current date -----> Allow create new poll. Don't allow delete this poll Allow edit final end date Don't allow edit start date, sub end date

When check poll: Start date <= current date < sub end date