Add python 2.6 requirements to Tox.

Also changes the tox config so the testing resources files can be used

tox.ini

@@ -1,4 +1,5 @@
 [tox]
+skipsdist=True
 envlist=py27-with-lxml,py27-with-old-lxml,py27-without-lxml,py26-with-lxml,py26-with-old-lxml,py26-without-lxml
 
 [testenv:py27-with-lxml]
@@ -22,22 +23,26 @@ deps=-rrequirements.txt
 basepython = /opt/python-2.6.9/bin/python
 deps=-rrequirements.txt
      -rrequirements-dev.txt
+     -rrequirements-2.6.txt
      lxml
 
 [testenv:py26-with-old-lxml]
 basepython = /opt/python-2.6.9/bin/python
 deps=-rrequirements.txt
      -rrequirements-dev.txt
+     -rrequirements-2.6.txt
      lxml<2.3
 
 [testenv:py26-without-lxml]
 basepython = /opt/python-2.6.9/bin/python
 deps=-rrequirements.txt
      -rrequirements-dev.txt
+     -rrequirements-2.6.txt
 
 [testenv]
-recreate = False
+recreate=False
 commands=
+    python setup.py develop
     py.test \
         --basetemp={envtmpdir} \
         {posargs}