Installs coveralls package from composer.json require-dev instead of during pipeline build.

Author: dsposito

.travis.yml

@@ -4,10 +4,6 @@ php:
   - '7.0'
   - '7.1'
 
-# Install test coverage package.
-install:
-  - composer require satooshi/php-coveralls
-
 # Install packages and create test coverage log directory.
 before_script:
   - composer install --dev --no-interaction

composer.json

@@ -17,6 +17,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^5.7",
+        "satooshi/php-coveralls": "^1.0",
         "squizlabs/php_codesniffer": "^2.8"
     },
     "autoload": {