Adding yamllinter to ci steps (#1556)

* Adding yaml linter to ci check

* Minor linting fixes from yamllint

* Changing CI to install python pkgs from requirements.txt

- adding in a secondary requirements.txt for tests
- moving yamllint to tests requirements

roles/bootstrap-os/tasks/bootstrap-coreos.yml

@@ -49,4 +49,3 @@
   pip:
     name: "{{ item }}"
   with_items: "{{pip_python_modules}}"
-

roles/bootstrap-os/tasks/main.yml

@@ -27,4 +27,3 @@
   hostname:
     name: "{{inventory_hostname}}"
   when: ansible_hostname == 'localhost'
-

roles/bootstrap-os/tasks/setup-pipelining.yml

@@ -6,4 +6,3 @@
     regexp: '^\w+\s+requiretty'
     dest: /etc/sudoers
     state: absent
-