misc/vote: new port -- a simple, transparent git based voting system

Teams like core and portmgr regularly hold votes on certain topics.
In the past these votes were held via email. This script tries to
lessen the burden of the secretary of those teams.

Vote's can be created using:

vote create <vote topic> <due date in YYYYMMDD> <some more text>

People can vote using

vote vote <vid> <yes/no/abstain>

People can also vote in-stead of other people

vote votefor <vid> <yes/no/abstain> <whom>

All votes and results are neatly tracked inside a git repository.