make success and failreason objects carry an influences hash

make success and failreason objects carry an influences hash

The hash will be used used to record a set of pages that influenced the
result of a pagespec match.

The influences are merged together when boolean and/or are encountered
in a pagespec. That means using a non-short-circuiting OR operator. And
so I use & and | when translating pagespecs, since those bitwise operators
can be overloaded. ("and" and "or" cannot, apparently).