Update legislators.rb

Added leadership role. Nicko's first pull (with help from Jeremy)!
Update legislator.rb

Added leadership role
Merge pull request #407 from nickom/patch-1

Patch 1
Added a bioguide_id option for easier debugging
Add term_start and term_end to default fields
don't downcase query strings in the ElasticSearch side, these will make it impossible to use AND/OR syntax
distrusting restart method
Added ICPSR IDs to legislators
Failure report, not exception
Fix merge conflict with sunlightlabs/congress master