chore(ci): improve Travis performance (#100)

Author: Kocal

.travis.yml

@@ -17,13 +17,11 @@ before_install:
   - npm i -g yarn
 
 install:
-  - yarn
-  - cd example && yarn && cd ..
+  - yarn install --frozen-lockfile
+  - cd example && yarn install --frozen-lockfile && cd ..
   - yarn cypress install
 
 before_script:
-  - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
   - cd example
   - yarn docs
   - yarn docs:docstrap
@@ -34,4 +32,4 @@ before_script:
 script:
   - yarn lint
   - yarn test -i && yarn codecov
-  - yarn cypress run --browser chrome --config watchForFileChanges=false
+  - yarn cypress run --config watchForFileChanges=false,video=false