WIP commit
Merge branch 'path_nameaddr_fix' into third_party_reg_dnssrv
Plumb through SIPResolver
Merge remote-tracking branch 'origin/dev' into third_party_reg_dnssrv

Conflicts:
	sprout/stateful_proxy.cpp
Enhance UTs so that app servers actually respond; clean up registrar_on_tsx_state as a result
Apply code review markups
Merge pull request #406 from Metaswitch/third_party_reg_dnssrv

[Reviewer: Matt] DNS-SRV lookup on third-party registration