Merge remote-tracking branch 'upstream/master' into cmake_qt5

.travis.yml

 language: cpp
+os:
+  - linux
+  - osx
 compiler:
   - gcc
   - clang
 script: mkdir build && cd build && cmake .. && make
-before_install:
-  - sudo apt-get update -qq
-  - sudo apt-get install -y qtmobility-dev libprotobuf-dev protobuf-compiler libqt4-dev build-essential
+install: ./travis-dependencies.sh
 cache: apt

travis-dependencies.sh

+#!/bin/bash
+
+if [[ $TRAVIS_OS_NAME == "osx" ]] ; then
+  brew update
+  brew install qt cmake protobuf
+else
+  sudo apt-get update -qq
+  sudo apt-get install -y qtmobility-dev libprotobuf-dev protobuf-compiler libqt4-dev
+fi