Druid- Truncate of relative datetime should happen even if value of unit is 0

More useful error message if index.html is missing when running `lein ring server`

ring server`  #2195

Automatically retry a BigQuery query if it times out 

Better error logging when BigQuery times out 

Update query button name

Additional fixes for intermittent BigQuery test failures 

bump version

Frontend dependencies updates

Add 'lein h2' to easily get a H2 console

use alpine as base image and subsequently fix npm build failures

Reduce intermittent CI failure rate

Bump dependencies 

Fix typos in docs

Clean up contrib guide 

Update babel-eslint + humanize-plus, fresh npm install --no-shrinkwrap, eliminates left-pad dependency.