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

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

* Enable netchecker app for CI postinstall tests
* Rework outputs and better coverage to the ping between pods post
intall test case. With netchecker deployed, the test covers hostnet
to hostnet and standard to standrad pods ping check as well.

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

For Travis CI and GCE, add a naive generator script into a markdown table.
Add GCE/Travis CI matrix docs.
Add CoreOS test cases.
Rework existing cases w/o loosing of coverage.
Rework postinstall tests to support CoreOS as well.

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