Add nightly integration test

[dmehra]

Desired:

• nightly integration test that uses the released versions of adapter and juttle
• nightly integration test that uses top-of-master for adapter and juttle (have npm pull from github)

What the test will actually do is still open; something lightweight that uses an adapter to write to, and read from, a docker container with the backend store, and visualize the result. As simple as read -last :hour: | reduce -every :minute: sum(value) | view timechart. If we later want to expand, file separate issues.

This will need to be set up for each supported adapter, namely:

• elastic
• influx
• posgresql (tbd: do we have do separately cover mysql and sqlite?)
• opentsdb
• graphite
• built-ins: file, http