Try travis testing on Python 3.5. Fix up Makefile to avoid pytest on 3.5

for now

.travis.yml

@@ -6,6 +6,7 @@ python:
   - '2.6'
   - '2.7'
   - '3.4'
+  - '3.5'
 
 install:
 - pip install -r requirements-dev.txt

Makefile

@@ -24,7 +24,11 @@ check:
 	$(MAKE) check-$$PYTHON_VERSION
 
 #: Tests for Python 2.7, 3.3 and 3.4
-check-2.7 check-3.3 check-3.4 check-3.5: pytest
+check-2.7 check-3.3 check-3.4: pytest
+	$(MAKE) -C test $@
+
+#: Tests for Python 3.5 - pytest doesn't work here
+check-3.5:
 	$(MAKE) -C test $@
 
 #:Tests for Python 2.6 (doesn't have pytest)