Move all lints tests to consolidated 'linters' tox environment

OpenStack-Infra has requested that lint tests be pipelined into the 'linters'
tox target in order to make more efficient use of nodepool resources.

This patch:
- adds a 'linters' target which executes all required lint tests.
- removes previously seperated tox targets for lint tests.

Change-Id: I931f5cddcf2e1006e662f8848e48accee42243ad

tox.ini

@@ -1,23 +1,12 @@
 [tox]
 minversion = 1.4.2
-envlist = ansible-lint,docs,pep8
+envlist = docs,linters
 skipsdist = True
 
 [testenv]
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
-[testenv:ansible-lint]
-setenv =
-  ANSIBLE_CONFIG = tests/ansible.cfg
-whitelist_externals = bash
-commands =
-  bash -c "find . -type f -regex '.*.y[a]?ml' -print0 | xargs -t -n1 -0 \
-    ansible-lint"
-  bash -c "find tests -type f -regex '.*.y[a]?ml' -print | xargs -t -n1 \
-    ansible-playbook --syntax-check -i tests/inventory \
-    -e rolename=$(basename $(pwd)) > /dev/null"
-
 [testenv:functional]
 commands =
   ansible-playbook -i tests/inventory tests/test.yaml
@@ -29,9 +18,6 @@ setenv =
 [testenv:docs]
 commands = python setup.py build_sphinx
 
-[testenv:pep8]
-commands = flake8
-
 [testenv:venv]
 commands = {posargs}
 
@@ -42,3 +28,18 @@ show-source = True
 ignore = E123,E125
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build
+
+[testenv:linters]
+setenv =
+  ANSIBLE_CONFIG = tests/ansible.cfg
+whitelist_externals = bash
+commands =
+  # PEP8 Lint Check
+  flake8
+  # Ansible Lint Check
+  bash -c "find . -type f -regex '.*.y[a]?ml' -print0 | xargs -t -n1 -0 \
+    ansible-lint"
+  # Ansible Syntax Check
+  bash -c "find tests -type f -regex '.*.y[a]?ml' -print | xargs -t -n1 \
+    ansible-playbook --syntax-check -i tests/inventory \
+    -e rolename=$(basename $(pwd)) > /dev/null"