Fix testrule after what seems to be a praw change

Or possibly a change in the reddit api return value
Add support for negative rules

Support negative rules, by prefixing ! in front of the header name. For
example !Username: batman will match objects where username does not
match 'batman'.
Add Userage rule field

The Userage rule field matches against the age of the author's
useraccount in days.
Add Userkarma rule field

The Userkarma field matches against the author's combined comment and
link karma.
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