Move pylint dependency to tox.ini

We do not run a gate job against oslo.vmware using pylint, so move the
dependency out of the synced requirements and into the tox environment
settings instead. If that's no longer useful, we can remove the tox
environment completely.

Change-Id: Ice3527b8d92137d04fd77e7e800a5875fa7fdaf2

test-requirements.txt

@@ -4,7 +4,6 @@
 
 # Hacking already pins down pep8, pyflakes and flake8
 hacking>=0.9.2,<0.10
-pylint>=1.3.0  # GNU GPL v2
 
 discover
 fixtures>=0.3.14

tox.ini

@@ -19,6 +19,9 @@ deps = -r{toxinidir}/requirements-py3.txt
 commands = flake8
 
 [testenv:pylint]
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+       pylint>=1.3.0
 commands = pylint oslo
 
 [testenv:docs]