Update travis configuration (#18)
Update travis configuration (#18)

* Don't test PHP versions without support

Remove from the travis CI configuration the versions of PHP that
don't have support anymore

* Remove PHP nightly version and add version 7.1

Remove from the travis CI configuration the nightly version of PHP
and add the last stable version (7.1)

* Test with Symfony 3.2 version

Add the symfony 3.2 version to be used in when tests are run by
travis CI

irozgar/gulp-rev-versions-bundle,irozgar/gulp-rev-versions-bundle