reuse runtests.sh and runtests.bat scripts in tox.ini

tox.ini

@@ -10,7 +10,7 @@ envlist = py26, py27, lucid, precise
 deps =
     -r{toxinidir}/.travis/requirements-latest.txt
 commands =
-    trial {posargs:--reporter=text scrapy}
+    {toxinidir}/bin/runtests.sh
 
 [testenv:lucid]
 basepython = python2.6
@@ -21,3 +21,7 @@ deps =
 basepython = python2.7
 deps =
     -r{toxinidir}/.travis/requirements-precise.txt
+
+[testenv:windows]
+commands =
+    {toxinidir}/bin/runtests.bat