use gdal-bin package for gdallocationinfo binary used for testing

Author: aatishnn

.travis.yml

@@ -4,6 +4,10 @@ python:
   - "3.2"
   - "3.3"
   - "3.6"
+before_install:
+  - sudo apt-get -qq update
+  - sudo apt-get install -y gdal-bin
+
 install:
   - pip install -r requirements.txt
 script: