chore: install Qt 5.6 in travis

.travis/build-ubuntu-14-04.sh

@@ -19,8 +19,8 @@
 # stop as soon as one of steps will fail
 set -e -o pipefail
 
-# Qt 5.5, since that's the lowest supported version
+# Qt 5.6, since that's the lowest supported version
-sudo add-apt-repository -y ppa:beineri/opt-qt551-trusty
+sudo add-apt-repository -y ppa:beineri/opt-qt562-trusty
 sudo apt-get update -qq
 
 # install needed Qt, OpenAL, opus, qrencode, GTK tray deps, sqlcipher
@@ -42,15 +42,15 @@ sudo apt-get install -y --force-yes \
     libtool \
     libvpx-dev \
     libxss-dev qrencode \
-    qt55base \
+    qt56base \
-    qt55script \
+    qt56script \
-    qt55svg \
+    qt56svg \
-    qt55tools \
+    qt56tools \
-    qt55xmlpatterns \
+    qt56xmlpatterns \
     pkg-config || yes
 
 # Qt
-source /opt/qt55/bin/qt55-env.sh || yes
+source /opt/qt56/bin/qt56-env.sh || yes
 
 # ffmpeg
 if [ ! -e "libs" ]; then mkdir libs; fi