Revert "Term starts at 1 instead of 0 and index starts at 1 instead of 0"

This reverts commit 558a866b0e06963725d01bcc4237713b3aa19059.
Fixed RaftLog interface
Renamed term to currentTerm and votedFor to lastVotedFor
Removed redundant methods
RaftLog starts at correct defaults
Re-read log on startup and persist votedFor and term. Fixes #4, Fixes #5