* Run CI triggers in one step
* Run all test matrix for triggers
* Switch back to g1-small

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

Includes tox support for running unit tests.
Small note added to getting-started guide for using
inventory_builder.py

Also adds manual-only unit test.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

Run 1 of each part1/2/special for Gitlab CI only for PRs
Remaining 2/3 of each stage are manual steps for master only (merges)

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

* Reduce default testcase to 2 nodes, add HA case.
* Adjust gen_matrix script for Travis/Gitlab CIs.
* Enable netchecker deploy foro gitlab CI.
* Sync other things from travis matrix and reorder them as build steps
  for pull requests, master branch, auto/manual.
* Do auto-step1 from part1 and manual step2,3 for branches/PRs.
* Do manual steps from part2, special for master merges.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>