Upgrade numpy to 1.8.1 for Py33 tests

See pandas-dev/pandas#11232

.travis.yml

@@ -6,10 +6,10 @@ env:
   - REPO_DIR=pandas
   - NOSE_ARGS="not slow and not disabled"
   matrix:
-  - VERSION=2.7.10 NUMPY_VERSION=1.7.1
-  - VERSION=3.3.5 NUMPY_VERSION=1.7.1
-  - VERSION=3.4.3 NUMPY_VERSION=1.7.1
-  - VERSION=3.5.0 NUMPY_VERSION=1.7.1 NOSE_ARGS="not slow and not network and not disabled"
+  - VERSION=2.7.10 NUMPY_VERSION=1.7.1 NUMPY_TEST_VERSION=1.7.1
+  - VERSION=3.3.5 NUMPY_VERSION=1.7.1 NUMPY_TEST_VERSION=1.8.1
+  - VERSION=3.4.3 NUMPY_VERSION=1.7.1 NUMPY_TEST_VERSION=1.8.1
+  - VERSION=3.5.0 NUMPY_VERSION=1.7.1 NUMPY_TEST_VERSION=1.9.3 NOSE_ARGS="not slow and not network and not disabled"
 install:
 - source terryfy/travis_tools.sh
 - get_python_environment macpython $VERSION venv
@@ -31,10 +31,8 @@ install:
 - cd ..
 script:
 - pip install nose
-# When pickling, numpy 1.7.1 read_array_header fails in Python 3.4
-- if [ -n "$(pyver_ge $VERSION 3.4.0)" ]; then
-  pip install -U -f $NIPY_WHEELHOUSE numpy;
-  fi
+# May need to upgrade numpy to run tests successfully
+- pip install numpy==$NUMPY_TEST_VERSION
 - mkdir tmp_for_test
 - cd tmp_for_test
 # Show pandas versions before tests