Improve CI test matrix

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>

tests/testcases/030_check-network.yml

@@ -3,8 +3,17 @@
 
   tasks:
 
+  - name: Force binaries directory for CoreOS
+    set_fact:
+      bin_dir: "/opt/bin"
+    when: ansible_os_family == "CoreOS"
+
+  - set_fact:
+      bin_dir: "/usr/local/bin"
+    when: ansible_os_family != "CoreOS"
+
   - name: Get pod names
-    shell: "/usr/local/bin/kubectl get pods -o json"
+    shell: "{{bin_dir}}/kubectl get pods -o json"
     register: pods
 
   - set_fact:
@@ -18,4 +27,4 @@
 
 
   - name: Ping between pods is working
-    shell: "/usr/local/bin/kubectl exec {{pod_names[0]}} -- ping -c 4 {{ pod_ips[1] }}"
+    shell: "{{bin_dir}}/kubectl exec {{pod_names[0]}} -- ping -c 4 {{ pod_ips[1] }}"