Add Gitlab-CI Configuration

Add Gitlab-CI Configuration

This change adda Gitlab-CI configuration for Barometer, mirroring all
the jobs currently in Jenkins:

 Docker build and pushes for containers on merge and tag:
   - barometer-collectd
   - barometer-collectd-latest
   - barometer-collectd-dma
   - barometer-collectd-grafana
   - barometer-collectd-influxdb
   - barometer-collectd-kafka
   - barometer-collectd-ves
   - barometer-collectd-snmp

 Builds on Merge Requests and Merges:
   - make clobber && make
   - Documentation builds & publishing

 Daily Jobs
   - barometer build & artifact upload
   - docker run barometer-collectd-tests

Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>
Change-Id: Ia5f8e33be537cbdd795da456d04cf6b18286c864