clearDnsCache API method
Merge branch 'cleardns' of git://github.com/roydekleijn/browsermob-proxy into roydekleijn-cleardns

Conflicts:
	README.md
Merge branch 'cleardns' of git://github.com/roydekleijn/browsermob-proxy into roydekleijn-cleardns

Conflicts:
	README.md