Added Whips

Added leadership_roles of Minority Whip and Majority Whip in both
chambers including previous sessions the current leaders held a
leadership role.

:horse_racing:
Merge pull request #113 from nickom/master

Added Whips
Removed 3 mistaken FEC IDs, reported by @jsfenfen in #111
Merge branch 'master' of github.com:unitedstates/congress-legislators
washington post
merge