Remove useless commands from travis

.travis.yml

@@ -4,16 +4,6 @@ node_js:
   - "4.5"
   - "6.6"
 
-env:
-  - CXX=g++-4.8
-
-addons:
-  apt:
-    sources:
-      - ubuntu-toolchain-r-test
-    packages:
-      - g++-4.8
-
 sudo: false
 
 services:
@@ -22,7 +12,6 @@ services:
 before_install: if [[ `npm -v` != 3* ]]; then npm i -g npm@3; fi
 
 before_script:
-  - npm install electron -g
   - npm run build
   - wget --no-check-certificate "https://download.cpy.re/ffmpeg/ffmpeg-release-3.0.2-64bit-static.tar.xz"
   - tar xf ffmpeg-release-3.0.2-64bit-static.tar.xz