Use language: generic

Trying to avoid the following issue:

ImportError: "from catkin_pkg.package import parse_package" failed: No
module named catkin_pkg.package
Make sure that you have installed "catkin_pkg", it is up to date and on
the PYTHONPATH.

Note that catkin_pkg is actually installed with python-catkin-pkg.

Author: Enrique Fernandez

.travis.yml

@@ -2,11 +2,7 @@
 # Author: Dave Coleman, Enrique Fernandez
 sudo: required
 dist: trusty
-language:
-  - cpp
-  - python
-python:
-  - "2.7"
+language: generic
 compiler:
   - gcc
 env: