swarm: add favicon for Swarm templates served by browser (#15958)

* swarm: added script to HTML header to create favicon addresses #153

* swarm: moved data blob direclty into link tag, removed script

* swarm: added favicon info to other html templates

* swarm: fixing test errors

* swarm: fixing favicon test

* swarm: fixing travis tests

* swarm: added script to HTML header to create favicon addresses #153

* swarm: moved data blob direclty into link tag, removed script

* swarm: added favicon info to other html templates

* swarm: fixing test errors

* swarm: fixing favicon test

* swarm: fixing travis tests