Add 'how' person got their term: election or succession.
Add vice-presidential terms for individuals who later served as president. Fixed a few parties.
Add entries for vice presidents who were previously members of Congress. Add some missing birthdays and genders.
Add entries for the remaining missing vice presidents. Add Barack Obama's middle name and suffix.
Nickname for Al Gore.
Merge pull request #43 from GPHemsley/presidential-succession

Fix terms for presidents who were elected in their own right after they finished their predecessor's term. Ensure no discontinuity in term dates.

Add 'how' person got their term: election or succession.

Addresses issue #41.
add vice presidents to executive.yaml (merging pull request #47 from @gphemsley)
assign new GovTrack IDs to vice presidents who never served as president or in Congress
Agnew mistakenly listed as a president
Add 'how' values for vice presidents. Fix Johnson/Wilson merge conflict.
Merge pull request #48 from GPHemsley/vicepres

Add 'how = election|appointment' values for vice presidents. Fix Johnson/Wilson merge conflict.