use yarn on ci

.travis.yml

@@ -12,10 +12,10 @@ before_install:
   - rvm install 2.2.5
   - rvm use 2.2.5
 install:
-  - npm install -g coveralls
+  - yarn global coveralls
   - gem install fastlane
-  - npm install
+  - yarn
 script:
-  - npm test
-  - npm run coverage
+  - yarn test
+  - yarn coverage
 sudo: false

yarn.lock

@@ -39,7 +39,7 @@ align-text@^0.1.1, align-text@^0.1.3:
     longest "^1.0.1"
     repeat-string "^1.5.2"
 
-amdefine@1.0.0, amdefine@>=0.0.4:
+amdefine@>=0.0.4, amdefine@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/amdefine/-/amdefine-1.0.0.tgz#fd17474700cb5cc9c2b709f0be9d23ce3c198c33"
 
@@ -2452,11 +2452,11 @@ regjsparser@^0.1.4:
   dependencies:
     jsesc "~0.5.0"
 
-remap-istanbul@^0.7.0:
-  version "0.7.0"
-  resolved "https://registry.yarnpkg.com/remap-istanbul/-/remap-istanbul-0.7.0.tgz#c360dadaea641dba734cb6a58cabe9ebd88a2858"
+remap-istanbul@^0.8.0:
+  version "0.8.4"
+  resolved "https://registry.yarnpkg.com/remap-istanbul/-/remap-istanbul-0.8.4.tgz#b4bfdfdbc90efa635e9a28b1f4a116e22c8c2697"
   dependencies:
-    amdefine "1.0.0"
+    amdefine "^1.0.0"
     gulp-util "3.0.7"
     istanbul "0.4.5"
     source-map ">=0.5.6"