Make running the tests like in travis-ci easier (#92)

* Move testing logic from travis.yml to tests-ci.sh script

This way we can share this logic between travis CI and other systems
like for example a docker container.

* Move logic to create a testing environment to tests-environment.sh

As with the logic to execute the tests, this way we can share this logic
with other systems to tests linuxdeployqt.

* Install Qt also in tests-environment.sh

No reason to keep it separate from the rest as far as I know

* Wait until the X server is up and running

Otherwise we get into a racy situation.

* Add Dockerfile to create a testing container

This container tries to emulate the environment we have in travis-ci,
this way we can test whatever is failing on the CI locally.

tests/tests-ci.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+set -x
+
+source /opt/qt*/bin/qt*-env.sh
+/opt/qt*/bin/qmake linuxdeployqt.pro
+make -j2
+
+mkdir -p linuxdeployqt.AppDir/usr/bin/
+cp /usr/local/bin/patchelf linuxdeployqt.AppDir/usr/bin/
+cp /usr/local/bin/appimagetool linuxdeployqt.AppDir/usr/bin/
+find linuxdeployqt.AppDir/
+export VERSION=continuous
+cp ./linuxdeployqt/linuxdeployqt linuxdeployqt.AppDir/usr/bin/
+./linuxdeployqt/linuxdeployqt linuxdeployqt.AppDir/linuxdeployqt.desktop -verbose=3 -appimage
+ls -lh
+find *.AppDir
+xpra start :99
+
+export DISPLAY=:99
+
+until xset -q
+do
+        echo "Waiting for X server to start..."
+        sleep 1;
+done
+
+bash -e tests/tests.sh

tests/tests-environment.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+set -e
+
+sudo add-apt-repository --yes ppa:beineri/opt-qt58-trusty
+sudo apt-get update -qq
+
+git clone https://github.com/NixOS/patchelf.git
+cd patchelf
+bash ./bootstrap.sh
+./configure
+make -j2
+sudo make install
+
+cd -
+
+sudo wget -c "https://github.com/probonopd/AppImageKit/releases/download/continuous/appimagetool-x86_64.AppImage" -O /usr/local/bin/appimagetool
+sudo chmod a+x /usr/local/bin/appimagetool
+
+sudo apt-get -y install qt58base qt58declarative qt58webengine binutils xpra