Replace trivial-validate.py with 3.0 version

As of this commit: https://github.com/diracdeltas/https-everywhere/commit/d921337ad87c11d80ef24fd17bfe5663cf120982
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'yan/master'
[cloudfront] fix Droplr issue

As reported in https://trac.torproject.org/projects/tor/ticket/8572,
some Droplr content does not display with the Cloudfront rule.