add(logging): Log and time various events

- Log what's happening at various appropriate levels
- Log the time it takes to download and the time it takes to write the
  image
fix(log): Log attrs separately instead of w/format
fix(logging): Don't drop precision on time values
fix(style): Fix style to match rest of project
Merge pull request #37 from rackerlabs/jay/AgentLogging

add(logging): Log and time various events