added protolite dependencies

libprotobuf-dev protobuf-compiler added to before_install directive

Author: serhatcevikel

.travis.yml

@@ -1,7 +1,9 @@
 before_install:
   - sudo add-apt-repository ppa:ubuntugis/ppa -y
   - sudo apt-get update -q
-  - sudo apt-get install -y libudunits2-dev proj-bin gdal-bin libgdal-dev libproj-dev libv8-dev libjq-dev
+  - sudo apt-get install -y libudunits2-dev proj-bin gdal-bin libgdal-dev libproj-dev 
+    libv8-dev libjq-dev libprotobuf-dev protobuf-compiler
+
 
 language: R
 cache: