Revert lz4 pinning (pandas-dev#355)

* Update .travis.yml

* Update setup.py

Author: bmoscon

.travis.yml

@@ -28,7 +28,7 @@ install:
   - pip install pandas==0.19.2
   - pip install decorator --upgrade
   - pip install enum34 --upgrade
-  - pip install lz4==0.8.2
+  - pip install lz4 --upgrade
   - pip install mock --upgrade
   - pip install mockextras
   - pip install pytest --upgrade

setup.py

@@ -94,7 +94,7 @@ def run_tests(self):
                     ],
     install_requires=["decorator",
                       "enum34",
-                      "lz4<=0.8.2",
+                      "lz4",
                       "mockextras",
                       "pandas<=0.19.2",
                       "pymongo>=3.0",