Fix STV chart results

Plots the results when only one person has voted, and correctly places
the Majority line
No votes, no table

Stops us throwing an error when nobody has yet cast their votes.
Properly assign rank

We were not properly setting the rank of options unless a round had only
a single possible option remaining
Remove skew from majority line

Majority is now purely at half the voter count, rather than slightly
above
Fix duplicates in Ranked table

The "#optionTable > tbody" had 2 results, and we were adding new rows to
both.
Merge pull request #106 from tpkelly/develop

Minor STV fixes