move pytest cli args to setup.cfg

setup.cfg

@@ -6,6 +6,8 @@ group = System Environment/Daemons
 
 [pytest]
 norecursedirs = examples lib local src
+testpaths = tests/
+addopts = --assert=plain
 
 [wheel]
 universal = 1

tox.ini

@@ -4,7 +4,7 @@ skipsdist = True
 
 [testenv]
 usedevelop = True
-commands = py.test {posargs:tests/} --assert=plain
+commands = py.test {posargs}
 deps =
   -rrequirements_test.txt
   py26: unittest2