WIP touch up environment.conf specs

(passing now)
WIP compile halts if environment has manifest conflict

An environment can be queried for whether it has a manifest conflict
(WIP) Fixed tests for Puppet::Settings::BaseSetting#value
Merge branch 'feature/master/pup-3069-add-defaultmanifest' of https://github.com/jpartlow/puppet into feature/master/pup-3069-add-defaultmanifest