Symfony HttpCache trait instead of class

[dbu]

When we stop php 5.3 support, we should convert the EventDispatchingHttpCache into a trait to reuse the logic with the FOSHttpCacheBundle kernel which extends a different HttpCache class and thus currently needs to copy the methods.

[ddeboer]

👍

[ddeboer]

We may want to restructure our abstract test case into one or more traits, too.

[ddeboer]

For the tests, see #218.

[dbu]

would traits actually help much? we need to extend methods of the HttpCache class. can a trait do that or does the user of the trait need to then tell which method wins?

[ddeboer]

As you can see in #233, overriding the methods is possible through the trait.