Crazy votes tallying

@jmileham @samandmoore 

Add votes table, remove votes columns from other tables.

Calculate votes scoped to parent, front page only shows the top tags w/o parents. (haven't built the query  that calculate global votes yet...)

weirdness: every tag exists as a top level tag
also, if i go to /foo/bar, where foo and bar have not been created before it will:
create foo top level tag, mapping, and a vote for that mapping
create bar top level tag, mapping, and vote for that mapping
create mapping of bar to parent foo, with a vote for that mapping

#HASHTAGFTW

can this just be `Mapping.top_ten`?