tweak travis

.travis.yml

@@ -35,10 +35,17 @@ install:
   - pip install -r requirements.txt
   - pip install .
   - pip install coveralls
+env:
+  global:
+    - PYTHONHASHSEED=0 
+  matrix:
+    # Enable this eventually after getting tensorflow to build on travis:
+    # - KERAS_BACKEND=theano KERAS_BACKEND=tensorflow
+    - KERAS_BACKEND=theano
 script:
   # download data and models, then run tests
   - mhcflurry-downloads fetch
   - mhcflurry-downloads info  # just to test this command works
-  - KERAS_BACKEND=theano PYTHONHASHSEED=0 nosetests test --with-coverage --cover-package=mhcflurry  && ./lint.sh
+  - nosetests test --with-coverage --cover-package=mhcflurry  && ./lint.sh
 after_success:
   coveralls