Update tox.ini. Fixes #1391

tox.ini

 [tox]
 envlist =
-    py27,py34,py35,py36,py37,py27-cffi,pypy,pypy3,py27-libuv,lint
+    py27,py35,py36,py37,py27-cffi,pypy,pypy3,py27-libuv,lint
 
 [testenv]
+extras =
+    test
+    events
+    dnspython
 deps =
-    greenlet
-    cython >= 0.24
-    coverage >= 4.0
-    psutil
     cffi
 whitelist_externals =
     *
 commands =
-    make basictest
+    python -m gevent.tests
 
 
 [testenv:py27-full]
 basepython = python2.7
 commands =
-    make alltoxtest
+    make allbackendtest
 
-[testenv:pypy]
-deps =
 
 [testenv:lint]
+skip_install = true
+skipsdist = true
 basepython =
-    python2.7
+    python3
 deps =
-    {[testenv]deps}
-    prospector
+    cffi
+    pylint
 commands =
-    make lint
+    pylint --rcfile=.pylintrc src/gevent
 
 [testenv:py27-cffi]
 basepython =
     python2.7
 setenv =
 	GEVENT_LOOP=libev-cffi
-commands =
-    make basictest
 
 [testenv:py27-libuv]
 basepython =
     python2.7
 setenv =
 	GEVENT_LOOP=libuv-cffi
-commands =
-    make basictest
 
 
 [testenv:leak]