Revert "Accept unescaped WP_Widget::get_field_id() and WP_Widget::get_field_name()"

This reverts commit b7ba83da2a4b2850004de76e6a3375d234ddcd7c.

For #159
Revert "Extend EscapeOutputSniff unit test with Widget code which should pass"

This reverts commit 1abb0024870bb139139108ba9512872611a622ad.

For #159
Merge pull request #174 from WordPress-Coding-Standards/issue-159-revert

Revert: EscapeOutputSniff should not flag echoing WP_Widget::get_field_id() and WP_Widget::get_field_name()