Add 'py27-minimal' tox target as replacement for 'py26-minimal'.

Drop spurious '[testenv:py26]' block.

tox.ini

@@ -2,7 +2,7 @@
 envlist =
 # Jython support pending 2.7 support, due 2012-07-15 or so.  See:
 # http://fwierzbicki.blogspot.com/2012/03/adconion-to-fund-jython-27.html
-    py27,py27-pure,pypy,py33,py34,py34-pure,py35,py35-pure,pypy3,coverage,docs
+    py27,py27-minimal,py27-pure,pypy,py33,py34,py34-pure,py35,py35-pure,pypy3,coverage,docs
 
 [mindeps]
 deps =
@@ -28,12 +28,16 @@ deps =
 commands =
     python setup.py -q test -q
 
-[testenv:py26]
+[testenv:py27-minimal]
+usedevelop = true
+basepython =
+    python2.7
 deps =
-    {[fulldeps]deps}
+    {[mindeps]deps}
     ordereddict
+    nose
 commands =
-    python setup.py -q test -q
+    nosetests -I persistentregistry -I security
 
 [testenv:py34-pure]
 basepython =