0.16.0 for Varnish 6.4

remove vmod_cookie

0.15.4 for Varnish 6.3

travis now uses the bionic repos

0.15.3 for Varnish 6.2

Remove vtree.h from EXTRA_DIST.

The dist* make targets had been failing, now passing.

0.15.2 for Varnish 6.1

reflect latest changes to the director API

0.15.1 for Varnish 6.0

Targets Varnish 6.0