Improve travis settings backported from v4 settings

.travis.yml

@@ -1,5 +1,7 @@
 language: php
 
+sudo: false
+
 php:
  - 5.3
  - 5.4
@@ -9,19 +11,31 @@ php:
  - hhvm
 
 matrix:
+ include:
+ - php: 5.3
+ env: COLLECT_COVERAGE=true
+ - php: 5.4
+ env: COLLECT_COVERAGE=true
+ - php: 5.5
+ env: COLLECT_COVERAGE=true
+ - php: 5.6
+ env: COLLECT_COVERAGE=true
+ - php: 7.0
+ - php: hhvm
  allow_failures:
  - php: 7.0
  fast_finish: true
 
+cache:
+ directories:
+ - $HOME/.composer/cache
+
 install:
- - travis_retry composer install
+ - travis_retry composer install --prefer-dist
 
 script:
  - phpunit --coverage-text --coverage-clover=coverage.clover
 
 after_script:
-- wget https://scrutinizer-ci.com/ocular.phar
-- if [ "$TRAVIS_PHP_VERSION" == "5.3" ]; then php ocular.phar code-coverage:upload --format=php-clover coverage.clover; fi
-- if [ "$TRAVIS_PHP_VERSION" == "5.4" ]; then php ocular.phar code-coverage:upload --format=php-clover coverage.clover; fi
-- if [ "$TRAVIS_PHP_VERSION" == "5.5" ]; then php ocular.phar code-coverage:upload --format=php-clover coverage.clover; fi
-- if [ "$TRAVIS_PHP_VERSION" == "5.6" ]; then php ocular.phar code-coverage:upload --format=php-clover coverage.clover; fi
+ - wget https://scrutinizer-ci.com/ocular.phar
+ - if [ "$COLLECT_COVERAGE" == "true" ]; then php ocular.phar code-coverage:upload --format=php-clover coverage.clover; fi