Merge pull request #2439 from solarce/sol-matrix-trusty-fix

Fixing matrix include so `os: linux` goes to trusty

.travis.yml

@@ -2,16 +2,14 @@ sudo: required
 
 language: python
 
-services:
-  - docker
-
 matrix:
   include:
     - os: linux
+      services:
+      - docker
     - os: osx
       language: generic
 
-
 install: ./script/travis/install
 
 script: