Remove the need for unset ... calls using AppRun file (#370)

linuxdeployqt.AppDir/AppRun

@@ -0,0 +1,5 @@
+#!/bin/bash
+# This file is being used so that users don't have to unset env vars manually
+HERE="$(dirname "$(readlink -f "${0}")")"
+unset QTDIR; unset QT_PLUGIN_PATH ; unset LD_LIBRARY_PATH
+exec "${HERE}/usr/bin/linuxdeployqt" "$@"

tests/tests-ci.sh

@@ -13,6 +13,7 @@ mkdir -p linuxdeployqt.AppDir/usr/{bin,lib}
 cp /usr/bin/{patchelf,desktop-file-validate} /usr/local/bin/{appimagetool,zsyncmake} linuxdeployqt.AppDir/usr/bin/
 cp ./bin/linuxdeployqt linuxdeployqt.AppDir/usr/bin/
 cp -r /usr/local/lib/appimagekit linuxdeployqt.AppDir/usr/lib/
+chmod +x linuxdeployqt.AppDir/AppRun
 find linuxdeployqt.AppDir/
 export VERSION=continuous
 if [ ! -z $TRAVIS_TAG ] ; then export VERSION=$TRAVIS_TAG ; fi