Enable qt tests in py27 env

tox.ini

@@ -5,6 +5,7 @@ skip_missing_interpreters = true
 [testenv]
 setenv =
     BITMESSAGE_HOME = {envtmpdir}
+    HOME = {envtmpdir}
     PYTHONWARNINGS = default
 deps = -rrequirements.txt
 commands =
@@ -22,6 +23,9 @@ commands =
     flake8 pybitmessage --count --select=E9,F63,F7,F82 \
     --show-source --statistics
 
+[testenv:py27]
+sitepackages = true
+
 [testenv:py27-doc]
 deps =
     .[docs]