Add test case for GH #455.

This bug has been fixed via adamkennedy/PPI#92
Add tests to cover false positives reported in GH #600.
Added test case to cover GH #496.

Even though PPI 1.216 did improve parsing of the augmented
assignment operators, this bug actually lies in Perl-Critic.
I suspect we need to make the Policy understand that the left
and right side of a postfix control should be treated as
separate expressions.
Add test case to cover GH #451.

This is fixed in the next release
of PPI via adamkennedy/PPI#92
Remove TODO marker from test. Code fixed in PPI.

See https://github.com/adamkennedy/PPI/issues/92