expunge python 2.6 (#3962)

* expunge python 2.6

* how did THAT happen

* remove another unsupported python from the tox envlist

* hypothesis can now be unconditionally imported
diff --git a/docs/development/getting-started.rst b/docs/development/getting-started.rst
index 0d7c91e..55dfd6c 100644
--- a/docs/development/getting-started.rst
+++ b/docs/development/getting-started.rst
@@ -75,10 +75,9 @@
 
     $ tox
     ...
-    ERROR:   py26: InterpreterNotFound: python2.6
      py27: commands succeeded
     ERROR:   pypy: InterpreterNotFound: pypy
-     py33: commands succeeded
+     py34: commands succeeded
      docs: commands succeeded
      pep8: commands succeeded