export ignore examples & tests in distribution

[staabm]

would be great if we wouldn't get the examples and tests via composer, when installing with --prefer-dist.

for background see https://www.reddit.com/r/PHP/comments/2jzp6k/i_dont_need_your_tests_in_my_production/

[phil-davis]

This is "a good thing" in general. But note that the unit tests from here were being run in sabre-io/dav - the tests/phpunit.xml there had:

      <testsuite name="sabre-event">
          <directory>../vendor/sabre/event/tests/</directory>
      </testsuite>

But actually no tests appear there any more. So actually those tests have not been running in sabre-io/dav CI.

A new version of phpunit is now reporting when there is a test suite defined that does not exist. CI started failing in sabre-io/dav. See sabre-io/dav#1316