Logging methods were renamed so they don't trigger go-vet warnings for
error() and Error() formatting.
Unit tests were updated to use new github.com/stretchr repo (was renamed
from stretchrcom)
Missing methods were added to Message mock object.
- Label graphs by their duration, not update period
- Extend to 60 units so they are either 10 minutes or an hour of data
- Improvements to retention information
- Change javascript calculations, fixes#9 (I hope)
