tox.ini: Add testing of multiple Tornado versions.

tox.ini

@@ -1,13 +1,34 @@
 [tox]
-envlist = py27,py34,py35,pypy,pypy3
+envlist = py27,py34,py35,pypy,pypy3,tornado42,tornado44,tornado45
 indexserver =
 	default = https://pypi.python.org/simple
 toxworkdir = build/tox
 skip_missing_interpreters = True
+use_develop = True
 
 [testenv]
 commands =
-    ./setup.py develop
-    nosetests []
+	nosetests -v
+
 deps =
-    -rrequires/testing.txt
+	-rrequires/testing.txt
+
+[testenv:tornado42]
+commands =
+	{envbindir}/pip install tornado>=4.2,<4.3
+	{[testenv]commands}
+
+[testenv:tornado43]
+commands =
+	{envbindir}/pip install tornado>=4.3,<4.4
+	{[testenv]commands}
+
+[testenv:tornado44]
+commands =
+	{envbindir}/pip install tornado>=4.4,<4.5
+	{[testenv]commands}
+
+[testenv:tornado45]
+commands =
+	{envbindir}/pip install tornado>=4.5,<4.6
+	{[testenv]commands}