Fixing syntax error in travis config file

Author: wndhydrnt

.travis.yml

@@ -6,6 +6,6 @@ python:
   - 3.3
 install:
   - if [[ $TRAVIS_PYTHON_VERSION == '2.6' ]]; then pip install unittest2; fi
-  - if [[ $TRAVIS_PYTHON_VERSION <= '2.7' ]]; then pip install python-memcached; else pip install python3-memcached; fi
+  - if [ $TRAVIS_PYTHON_VERSION == '2.6' ] || [ $TRAVIS_PYTHON_VERSION == '2.7' ]; then pip install python-memcached; else pip install python3-memcached; fi
   - pip install -r requirements-dev.txt --use-mirrors
 script: nosetests