Better mark loading from file. Now using YAML so works with multiple hosts.

[barn]

Load "saved" marks from YAML, so we can have per host marks, rather than
just one giant apply to all list.

[ben@laptop:~]% cat .rvc-marks.yaml
vc01.example.org: { alice: /vc01.example.org/dc01/host/alice.puppetlabs.lan/,
                                    bob:   /vc01.example.org/dc01/host/bob.puppetlabs.lan/ }
test.example.org: { data:  /vc02/dc02/datastore }

Then on vc01.example.org it will load in those two marks as CLI inception.