Fix %files section to not claim ownership of bindir and mandir

Addresses: #50 basho/riak_cs#554

The %files section had to general a case for both (s)bindir and mandir, specifying the actual directory rather than the contents of the directory.  This change simply changes those
two lines to be the `<dir>/*` style as recommended in the [fedora package maintainers documentation](http://fedoraproject.org/wiki/How_to_create_an_RPM_package#.25files_section)