travis: attempt to prioritize our cmake build

.travis/before_install.sh

@@ -2,6 +2,9 @@
 
 if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
 
+    # CMake
+    sudo add-apt-repository ppa:olive-editor/cmake -y
+
     # Qt 5.11
     sudo add-apt-repository ppa:beineri/opt-qt-5.11.0-xenial -y
 
@@ -11,9 +14,6 @@ if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
     # OpenColorIO
     sudo add-apt-repository ppa:olive-editor/opencolorio -y
 
-    # CMake
-    sudo add-apt-repository ppa:olive-editor/cmake -y
-
     # Update apt
     sudo apt-get update -qq