Update travis build

.travis.yml

@@ -5,24 +5,21 @@ node_js:
 addons:
   apt:
     sources:
-      - llvm-toolchain-trusty-5.0
+      - ubuntu-toolchain-r-test
     packages:
-      - clang-5.0
+      - g++-6
 env:
   global:
-    - CXX=clang++-5.0
-    - CC=clang-5.0
+    - CC=gcc-6
+    - CXX=g++-6
 install:
-  # on node 12 opencv4nodejs and mjpeg-consumer cannot be installed
-  - if [[ `node --version` != v12* ]]; then
-      printf "while [ true ]; do\nsleep 30\necho 'Building OpenCV'\ndone" > ping.sh;
-      bash ping.sh &
-      echo $! > ping.pid;
-      npm i opencv4nodejs > /dev/null 2>&1;
-      kill `cat ping.pid`;
-
-      npm install --no-save mjpeg-consumer;
-    fi
+  - |
+    printf "while [ true ]; do\nsleep 30\necho 'Building OpenCV'\ndone" > ping.sh;
+    bash ping.sh &
+    echo $! > ping.pid;
+    npm i opencv4nodejs > /dev/null 2>&1;
+    kill `cat ping.pid`;
+  - npm install --no-save mjpeg-consumer;
   - npm install
 script:
   - npm run test && npm run e2e-test