setup Travis-CI for indigoDock

[luzpaz]

It's helpful to to test builds via Continuous Integration services. Ubuntu Trusty is the default Linux distro that Travis-CI uses.
We can get Travis-CI to install Qt5.6 via adding something like:

# Linux
- if [ $TRAVIS_OS_NAME == linux ]; then 
      sudo apt-add-repository ppa:beineri/opt-qt56-trusty -y;
      sudo apt-get update -qq; 
      sudo apt-get install -y qt56base qt56declarative qt56tools;
  fi

We can also look at other Qt5 projects that use Travis like:

• https://github.com/pbek/QOwnNotes/blob/develop/.travis.yml
• https://forum.qt.io/topic/50340/installing-qt-5-4-dev-packages-in-travis-ci/16

[nitramr]

I'm using Xenial Xerus as distro. Not sure if it can run on my system.

[luzpaz]

I'm not talking about running it locally.