remove unused  calculation in leaders_in method.
leaders() should return an empty list in case of an empty result set.
Merge pull request #7 from simonz05/leaders-return-type

leaders() should return an empty list in case of an empty result set.
Merge pull request #8 from simonz05/unused-calculation

remove unused  calculation in leaders_in method.
Merge branch 'master' into members_only-option
add _parse_raw_leaders helper function.

_parse_raw_leaders handles the common logic for parsing results data
from a leader query.