travis: Rewrite the CI config to use platform matrix

.travis.yml

@@ -1,10 +1,14 @@
 language: cpp
-before_install:
+
-- sudo apt-get update -qq
+matrix:
-- sudo apt-get install -qq libxtst-dev
+  include:
-- sudo apt-get install -qq qtdeclarative5-dev
+    - os: linux
-- sudo apt-get install -qq libavahi-compat-libdnssd-dev
+      addons:
-script: sh -x ./clean_build.sh
+        apt:
-# skip install phase since we have a customized install package
+          packages:
-# creation tool for each supported platform
+            - libxtst-dev
+            - qtdeclarative5-dev
+            - libavahi-compat-libdnssd-dev
+      script: sh -x ./clean_build.sh
+
 install: true