run bashate as part of the linters gate

Also keep pep8 as a compat wrapper around it, to be remove
once zuul config has been adjusted to run linters instead.

Change-Id: I1e1be5bd2cd5a3f6b1c0f68ccf29e536b1743311

tox.ini

@@ -39,19 +39,24 @@ commands = validate-constraints {toxinidir}/global-requirements.txt {toxinidir}/
 [testenv:validate-projects]
 commands = validate-projects {toxinidir}/projects.txt
 
+# TODO remove once zuul reconfigured to run linters on gate
 [testenv:pep8]
-deps = hacking>=1.0.0
-basepython = python3
-commands = flake8
+deps = {[testenv:linters]deps}
+whitelist_externals = {[testenv:linters]whitelist_externals}
+commands = {[testenv:linters]commands}
 
-[testenv:bashate]
+[testenv:linters]
+deps =
+    hacking>=1.0.0
+    bashate>=0.5.1
 whitelist_externals = bash
-# E006: Line too long:
-# E010: The "do" should be on same line as for
-commands = bash -c "find {toxinidir}/tools      \
-                        -type f                 \
-                        -name \*.sh             \
-                        -print0 | xargs -0 bashate -v -iE006,E010"
+basepython = python3
+commands =
+    flake8
+    bash -c "find {toxinidir}/tools      \
+                 -type f                 \
+                 -name \*.sh             \
+                 -print0 | xargs -0 bashate -v -iE006,E010"
 
 [testenv:docs]
 commands = python setup.py build_sphinx