Add vote dates and sort by date

...ol/tests/RepresentativeDetailTest/test_votes_display.html

...ativeListTest.test_page1_paginateby12_displaylist/content

...st.test_page1_paginateby12_displaylist_searchjoly/content

...ativeListTest.test_page1_paginateby24_displaygrid/content

...ativeListTest.test_page2_paginateby12_displaylist/content

...ativeListTest.test_page2_paginateby24_displaylist/content

memopol/views.py

static/less/legislature.less

templates/representatives/representative_detail.haml