Hostnames for A records

[kozyraki]

For the A records, the hostname should be task.framework.domain
Ie task.marathon.mesos. we should not have task.mesos. The framework name should be skipped only if there is no framework name available. Task and framework names should only be modified to remove invalid characters for hostnames.

For SRV records, the service name should be .... Ie, _search._tcp.marathon.mesos. Unless of course there is no framework name in which case we skip that field. This amounts to defining a subdomain per framework. Task and framework names should only be modified to remove invalid characters for hostnames.